Algorithms/JavaAlgorithms
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In this commit I have:

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Added JavaDoc to every package except for "heaps"
This commit is contained in:
zacharyjones123 2017-04-18 07:57:17 -07:00
parent 94871b7e6a
commit 9411d5be56
29 changed files with 1406 additions and 425 deletions
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7
.classpath Normal file
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@ -0,0 +1,7 @@
<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry excluding="data_structures/" kind="src" path=""/>
<classpathentry kind="src" path="data_structures"/>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
<classpathentry kind="output" path="bin"/>
</classpath>

1
.gitignore vendored Normal file
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@ -0,0 +1 @@
/bin/

17
.project Normal file
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@ -0,0 +1,17 @@
<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
<name>Java</name>
<comment></comment>
<projects>
</projects>
<buildSpec>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.eclipse.jdt.core.javanature</nature>
</natures>
</projectDescription>

74
BinarySearch.java Normal file
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import java.util.Scanner;
/**
* Implements a Binary Search in Java
*
* @author unknown
*/
class BinarySearch
{
/**
* This method implements the Binary Search
*
* @param array The array to make the binary search
* @param key The number you are looking for
* @param lb The lower bound
* @param up The upper bound
* @return the location of the key
**/
public static int BS(int array[], int key, int lb, int ub)
{ if (lb>ub)
{
return -1;
}
int mid=(lb+ub)/2;
if (key<array[mid])
{
return (BS(array, key, lb, mid-1));
}
else if (key>array[mid])
{
return (BS(array, key, mid+1, ub));
}
else
{
return mid;
}
}
/**
* This is the main method of Binary Search
*
* @author Unknown
* @param args Command line parameters
*/
public static void main(String[] args)
{
Scanner input=new Scanner(System.in);
int array[]=new int[10] ;
int key;
//Input
System.out.println("Enter an array of 10 numbers : ");
for (int i=0; i<10 ;i++ )
{
array[i]=input.nextInt();
}
System.out.println("Enter the number to be searched : ");
key=input.nextInt();
int index=BS(array, key, 0, 9);
if (index!=-1)
{
System.out.println("Number found at index number : " + index);
}
else
{
System.out.println("Not found");
}
}
}

32
BinaryToDecimal.java Normal file
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@ -0,0 +1,32 @@
import java.util.Scanner;
/**
* This class converts a Binary number to a Decimal number
*
* @author Unknown
*
*/
class BinaryToDecimal
{
/**
* Main Method
*
* @param args Command line arguments
*/
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
int n,k,d,s=0,c=0;
n=sc.nextInt();
k=n;
while(k!=0)
{
d=k%10;
s+=d*(int)Math.pow(2,c++);
k/=10;
}
System.out.println("Binary number:"+n);
System.out.println("Decimal equivalent:"+s);
}
}

50
BubbleSort.java Normal file
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@ -0,0 +1,50 @@
import java.util.Scanner;
/**
* This class implements BubbleSort
*
* @author Unknown
*
*/
class BubbleSort
{
/**
* Main Method
*
* @param args Command line arguments
*/
public static void main(String[] args)
{
int array[]=new int[6];
Scanner input=new Scanner(System.in);
//Input
System.out.println("Enter any 6 Numbers for Unsorted Array : ");
for(int i=0; i<6; i++)
{
array[i]=input.nextInt();
}
//Sorting
for(int i=0; i<5; i++)
{
for(int j=i+1; j<6; j++)
{
if(array[j]>array[i])
{
int temp=array[j];
array[j]=array[i];
array[i]=temp;
}
}
}
//Output
for(int i=0; i<6; i++)
{
System.out.print(array[i]+"\t");
}
}
}

31
DecimalToBinary.java Normal file
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@ -0,0 +1,31 @@
import java.util.Scanner;
/**
* This class converts a Decimal number to a Binary number
*
* @author Unknown
*
*/
class DecimalToBinary
{
/**
* Main Method
*
* @param args Command Line Arguments
*/
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
int n,k,s=0,c=0,d;
n=sc.nextInt();
k=n;
while(k!=0)
{
d=k%2;
s=s+d*(int)Math.pow(10,c++);
k/=2;
}//converting decimal to binary
System.out.println("Decimal number:"+n);
System.out.println("Binary equivalent:"+s);
}
}

31
DecimalToOctal.java Normal file
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@ -0,0 +1,31 @@
import java.util.Scanner;
/**
* This class converts Decimal numbers to Octal Numbers
*
* @author Unknown
*
*/
class Decimal_Octal
{
/**
* Main Method
*
* @param args Command line Arguments
*/
public static void main(String[] args)
{
Scanner sc=new Scanner(System.in);
int n,k,d,s=0,c=0;
n=sc.nextInt();
k=n;
while(k!=0)
{
d=k%8;
s+=d*(int)Math.pow(10,c++);
k/=8;
}
System.out.println("Decimal number:"+n);
System.out.println("Octal equivalent:"+s);
}
}

19
Factorial.java
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@ -1,7 +1,19 @@
import java.util.Scanner;
/**
* This program will print out the factorial of any non-negative
* number that you input into it.
*
* @author Unknown
*
*/
public class Factorial{
/**
* The main method
*
* @param args Command line arguments
*/
public static void main(String[] args){
Scanner input = new Scanner(System.in);
//Prompt user to enter integer
@ -20,7 +32,12 @@ public class Factorial{
}
}
//Factorial method
/**
* Recursive Factorial Method
*
* @param n The number to factorial
* @return The factorial of the number
*/
public static long factorial(int n){
if (n==0){

19
FindingPrimes.java
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@ -1,12 +1,27 @@
/*
* The Sieve of Eratosthenes is an algorithm used to find prime numbers, up to a given value.
/**
* The Sieve of Eratosthenes is an algorithm use to find prime numbers,
* up to a given value.
* Illustration: https://upload.wikimedia.org/wikipedia/commons/b/b9/Sieve_of_Eratosthenes_animation.gif
* (This illustration is also in the github repository)
*
* @author Unknown
*
*/
public class FindingPrimes{
/**
* The Main method
*
* @param args Command line arguments
*/
public static void main(String args[]){
SOE(20); //Example: Finds all the primes up to 20
}
/**
* The method implementing the Sieve of Eratosthenes
*
* @param n Number to perform SOE on
*/
public static void SOE(int n){
boolean sieve[] = new boolean[n];

69
HeapSort.java
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@ -1,24 +1,22 @@
import java.util.Scanner;
/**
* Heap Sort Algorithm. Implements MinHeap
* Heap Sort Algorithm
* Implements MinHeap
*
* @author Unknown
*
*/
public class HeapSort {
/**
* array to store heap.
*/
/** Array to store heap */
private int[] heap;
/**
* size of heap.
*/
/** The size of the heap */
private int size;
/**
* Constructor.
* Constructor
*
* @param heap
* array of unordered integers
* @param heap array of unordered integers
*/
public HeapSort(int[] heap) {
this.setHeap(heap);
@ -26,32 +24,28 @@ public class HeapSort {
}
/**
* Sets this.size with {@code length).
* Setter for variable size
*
* @param length
* integer length of heap
* @param length new size
*/
private void setSize(int length) {
this.size = length;
}
/**
* Sets Heap with {@code heap}.
* Setter for variable heap
*
* @param heap
* array of unordered elements
* @param heap array of unordered elements
*/
private void setHeap(int[] heap) {
this.heap = heap;
}
/**
* Swaps index of {@code first} with {@code second}.
* Swaps index of first with second
*
* @param first
* index to swap {@code second} with
* @param second
* index to swap {@code first} with
* @param first First index to switch
* @param second Second index to switch
*/
private void swap(int first, int second) {
int temp = this.heap[first];
@ -60,12 +54,10 @@ public class HeapSort {
}
/**
* Heapifies subtree from {@code top} as root to {@code last} as last child.
* Heapifies subtree from top as root to last as last child
*
* @param rootIndex
* index of root
* @param lastChild
* index of last child
* @param rootIndex index of root
* @param lastChild index of last child
*/
private void heapSubtree(int rootIndex, int lastChild) {
int leftIndex = rootIndex * 2 + 1;
@ -91,10 +83,9 @@ public class HeapSort {
}
/**
* Makes heap with {@code root} as root.
* Makes heap with root as root
*
* @param root
* index of root of heap
* @param root index of root of heap
*/
private void makeMinHeap(int root) {
int leftIndex = root * 2 + 1;
@ -111,9 +102,9 @@ public class HeapSort {
}
/**
* Gets the root of this.heap.
* Gets the root of heap
*
* @return root of this.heap
* @return root of heap
*/
private int getRoot() {
this.swap(0, this.size - 1);
@ -123,9 +114,9 @@ public class HeapSort {
}
/**
* Sorts this.heap with heap sort; displays ordered elements to console.
* Sorts heap with heap sort; displays ordered elements to console.
*
* @return {@code sorted} array of sorted elements
* @return sorted array of sorted elements
*/
public final int[] sort() {
this.makeMinHeap(0); // make min heap using index 0 as root.
@ -140,7 +131,7 @@ public class HeapSort {
}
/**
* Gets input to sort.
* Gets input to sort
*
* @return unsorted array of integers to sort
*/
@ -157,10 +148,9 @@ public class HeapSort {
}
/**
* Prints elements in heap.
* Prints elements in heap
*
* @param heap
* array representing heap
* @param heap array representing heap
*/
public static void printData(int[] heap) {
System.out.println("Sorted Elements:");
@ -170,10 +160,9 @@ public class HeapSort {
}
/**
* Main method.
* Main method
*
* @param args
* the command line arguments
* @param args the command line arguments
*/
public static void main(String[] args) {
int[] heap = getInput();

49
InsertionSort.java Normal file
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@ -0,0 +1,49 @@
import java.util.Scanner;
/**
* This class implements Insertion Sort
*
* @author Unknown
*
*/
class InsertionSort
{
/**
* Main Method
*
* @param args Command line arguments
*/
public static void main(String[] args)
{
int array[]=new int[6];
Scanner input=new Scanner(System.in);
//Input
System.out.println("Enter any 6 Numbers for Unsorted Array : ");
for(int i=0; i<6; i++)
{
array[i]=input.nextInt();
}
//Sorting
for(int i=0; i<6; i++)
{
int temp=array[i];
int j=i-1;
while(j>=0 && temp<array[j] )
{
array[j+1]=array[j];
j--;
}
array[j+1]=temp;
}
//Output
for(int i=0; i<6; i++)
{
System.out.print(array[i]+"\t");
}
}
}

55
InsertionSortInteger.java Normal file
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@ -0,0 +1,55 @@
/**
* This is my implementation of an insertion sort.
*
* I decided to do this when i didn't feel comfortable enough about implementing
* different types of sorts, so this is my trial and error to try and get myself to implement
* the various sorts correctly.
*
* @author Kody C. Kendall
*
*/
public class InsertionSortInteger {
public int[] insertionIntArraySort(int[] initialArray){
int[] sortedArray = new int[initialArray.length];
//Marking first element as sorted.
sortedArray[0] = initialArray[0];
//For each element in the initialArray
for (int index = 1; index < initialArray.length; index++){
//Finding the last index that was sorted
int lastSortedIndex = index;
//Extracting the next element to be compared w/ other sorted elements from initial array
int extractedElement = initialArray[index];
//Compare the values of the sorted index to the current extractedElement
for (lastSortedIndex = index; lastSortedIndex > 0; lastSortedIndex--){
//If our extracted element is smaller than element to the right, switch them.
if (sortedArray[lastSortedIndex-1] > extractedElement){
//move the element to the left of extractedElement to the right in sortedArray
sortedArray[lastSortedIndex] = sortedArray[lastSortedIndex-1];
//And move the current extractedElement to the left one (since it's smaller).
sortedArray[lastSortedIndex-1] = extractedElement;
}
else{
//insert element where it is.
sortedArray[lastSortedIndex] = extractedElement;
//Terminating loop since element is in the right spot.
break;
}
}
}
return sortedArray;
}
}

19
LinearSearch.java
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@ -1,7 +1,10 @@
import java.util.Scanner;
public class LinearSearch{
//Main method
/**
* The main method
* @param args Command line arguments
*/
public static void main(String[] args){
Scanner input = new Scanner(System.in);
@ -27,7 +30,13 @@ public class LinearSearch{
}
//Linear search method
/**
* Linear search method
*
* @param list List to be searched
* @param key Key being searched for
* @return Location of the key
*/
public static int linearsearch(int[] list, int key){
for (int i = 0; i< list.length; i++){
@ -37,7 +46,11 @@ public class LinearSearch{
} return -1;
}
//Helper method
/**
* Helper Method
*
* @param a array to be printed
*/
public static void printarray(int[] a){
System.out.print("The array is: ");
for( int d: a){

32
MergeSort.java
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@ -1,18 +1,22 @@
import java.util.Scanner;
/**
* Merge Sort
* This class implements MergeSort
* @author Unknown
*
*/
public class MergeSort {
/** Array for mergeSort*/
private int[] array;
/** Temp Merge Array*/
private int[] tempMergArr;
/** Length of the array*/
private int length;
/**
* Sorts {@code inputArr} with merge sort algorithm.
* Sorts inputArr with merge sort algorithm
*
* @param inputArr
* @param inputArr Array to be sorted
*/
public final void sort(int inputArr[]) {
this.array = inputArr;
@ -22,12 +26,10 @@ public class MergeSort {
}
/**
* Partitions Array into recursively smaller pieces.
* Partitions Array into recursively smaller pieces
*
* @param lowerIndex
* lower bound to include in the first partition
* @param higherIndex
* upper bound to include in the third partition
* @param lowerIndex lower bound to include in the first partition
* @param higherIndex upper bound to include in the third partition
*/
private void mergeSort(int lowerIndex, int higherIndex) {
if (lowerIndex < higherIndex) {
@ -42,11 +44,11 @@ public class MergeSort {
}
/**
* Merges partitions.
* Merges partitions
*
* @param lowerIndex
* @param middle
* @param higherIndex
* @param lowerIndex The lower index
* @param middle The middle index
* @param higherIndex The higher index
*/
private void mergeParts(int lowerIndex, int middle, int higherIndex) {
for (int i = lowerIndex; i <= higherIndex; i++) {
@ -74,7 +76,7 @@ public class MergeSort {
}
/**
* Gets input to sort.
* Gets input to sort
*
* @return unsorted array of integers to sort
*/
@ -91,9 +93,9 @@ public class MergeSort {
}
/**
* Main Method.
* Main Method
*
* @param args
* @param args Command line arguments
*/
public static void main(String args[]) {
int[] inputArr = getInput();

33
Quicksort.java
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@ -1,7 +1,19 @@
import java.util.Scanner;
/**
* Implementation of QuickSort
*
* @author Unknown
*
*/
public class Quicksort{
/**
* The main method
*
* @param args Command line arguments
*/
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int[] array;
@ -28,7 +40,13 @@ public class Quicksort{
System.out.println();
}
//Quicksort Method
/**
* QuickSort method
*
* @param ar Array to perform QuickSort
* @param start Start of the array
* @param end End of the array
*/
public static void quicksort(int[] ar, int start, int end){
int[] array;
@ -54,7 +72,13 @@ public class Quicksort{
}
}
//Helper methods
/**
* Helper Method 1 - Swaps elements of an array
*
* @param ar Array to be used
* @param index1 Index 1 to be switched with Index 2
* @param index2 Index 2 to be switched with Index 1
*/
public static void swap(int[] ar, int index1, int index2){
int temp = ar[index1];
@ -62,6 +86,11 @@ public class Quicksort{
ar[index2] = temp;
}
/**
* Helper Method 2 - Prints the elements of an array
*
* @param array Array to be printed
*/
public static void printarray(int[] array){
for (int data : array){

47
ReverseString.java Normal file
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@ -0,0 +1,47 @@
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
/**
* This method produces a reversed version of a string
*
* @author Unknown
*
*/
class ReverseString
{
/**
* This method reverses the string str and returns it
* @param str String to be reversed
* @return Reversed string
*/
static String reverseString(String str)
{
String reverse=" ";
if(str.length()==1)
{
return str;
}
else
{
reverse=reverse+str.charAt(str.length()-1)+reverseString(str.substring(0,str.length()-1));
return reverse;
}
}
/**
* Main Method
*
* @param args Command line arguments
* @throws IOException Exception thrown because of BufferedReader
*/
public static void main(String args[]) throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the string");
String srr=br.readLine();
System.out.println("Reverse="+reverseString(srr));
}
}

52
SelectionSort.java Normal file
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@ -0,0 +1,52 @@
import java.util.Scanner;
/**
* This class implements Selection Sort
*
* @author Unknown
*
*/
class SelectionSort
{
/**
* Main method
*
* @param args Command line arguments
*/
public static void main(String[] args)
{
int array[]=new int[6];
Scanner input=new Scanner(System.in);
//Input
System.out.println("Enter any 6 Numbers for Unsorted Array : ");
for(int i=0; i<6; i++)
{
array[i]=input.nextInt();
}
//Sorting
for(int i=0; i<6; i++)
{
int min=i;
for(int j=i+1; j<6; j++)
{
if(array[j]<array[min])
{
min=j;
}
}
int temp=array[i];
array[i]=array[min];
array[min]=temp;
}
//Output
for(int i=0; i<6; i++)
{
System.out.print(array[i]+"\t");
}
}
}

22
bfs.java
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@ -1,7 +1,20 @@
import java.util.*;
public class App{
/**
* Implementation of a Breadth First Search
*
* @author Unknown
*
*/
public class bfs{
/**
* The BFS implemented in code to use.
*
* @param a Structure to perform the search on
* @param vertices The vertices to use
* @param source The Source
*/
public static void bfs(byte [][] a,int vertices,int source){ //passing adjacency matrix and no of vertices
byte []b=new byte[vertices]; //flag container containing status of each vertices
Arrays.fill(b,(byte)-1); //status initialization
@ -10,7 +23,7 @@ public class App{
0 = waiting
1 = processed */
Queue <Integer> st=new LinkedList<>(); //operational stack
Queue <Integer> st=new Queue<>(); //operational stack
st.add(source); //assigning source
while(!st.isEmpty()){
b[st.peek()]=(byte)0; //assigning waiting status
@ -26,6 +39,11 @@ public class App{
}
/**
* The main method
*
* @param args Command line arguments
*/
public static void main(String args[]){
Scanner in=new Scanner(System.in);
int vertices=in.nextInt(),source=in.nextInt();

13
countwords.java
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@ -1,6 +1,19 @@
import java.util.Scanner;
/**
* You enter a string into this program, and it will return how
* many words were in that particular string
*
* @author Unknown
*
*/
class CountTheWords
{
/**
* The main method
*
* @param args Command line arguments
*/
public static void main(String args[])
{
System.out.println("Enter the string");

124
data_structures/BinaryTree.java
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@ -1,11 +1,35 @@
//A binary tree is a data structure in which an element has two successors(children)
//The left child is usually smaller than the parent, and the right child is usually bigger
/**
* This entire class is used to build a Binary Tree data structure.
* There is the Node Class and the Tree Class, both explained below.
*
* @author Unknown
*
*/
/**
* This class implements the nodes that will go on the Binary Tree.
* They consist of the data in them, the node to the left, the node
* to the right, and the parent from which they came from.
*
* @author Unknown
*
*/
class Node{
/** Data for the node */
public int data;
/** The Node to the left of this one */
public Node left;
/** The Node to the right of this one */
public Node right;
/** The parent of this node */
public Node parent;
/**
* Constructor of Node
*
* @param value Value to put in the node
*/
public Node(int value){
data = value;
left = null;
@ -14,13 +38,33 @@ class Node{
}
}
/**
* A binary tree is a data structure in which an element
* has two successors(children). The left child is usually
* smaller than the parent, and the right child is usually
* bigger.
*
* @author Unknown
*
*/
class Tree{
/** The root of the Binary Tree */
private Node root;
/**
* Constructor
*/
public Tree(){
root = null;
}
//Returns the node if it finds it, otherwise returns the parent
/**
* Method to find a Node with a certain value
*
* @param key Value being looked for
* @return The node if it finds it, otherwise returns the parent
*/
public Node find(int key){
Node current = root;
Node last = root;
@ -37,7 +81,11 @@ class Tree{
return last;
}
//Inserts the given value
/**
* Inserts certain value into the Binary Tree
*
* @param value Value to be inserted
*/
public void put(int value){
Node newNode = new Node(value);
if(root == null)
@ -60,7 +108,12 @@ class Tree{
}
}
//Deletes the given value
/**
* Deletes a given value from the Binary Tree
*
* @param value Value to be deleted
* @return If the value was deleted
*/
public boolean remove(int value){
//temp is the node to be deleted
Node temp = find(value);
@ -84,34 +137,34 @@ class Tree{
//Two children
else if(temp.left != null && temp.right != null){
Node succesor = findSuccesor(temp);
Node successor = findSuccessor(temp);
//The left tree of temp is made the left tree of the successor
succesor.left = temp.left;
succesor.left.parent = succesor;
successor.left = temp.left;
successor.left.parent = successor;
//If the successor has a right child, the child's grandparent is it's new parent
if(succesor.right != null && succesor.parent != temp){
succesor.right.parent = succesor.parent;
succesor.parent.left = succesor.right;
succesor.right = temp.right;
succesor.right.parent = succesor;
if(successor.right != null && successor.parent != temp){
successor.right.parent = successor.parent;
successor.parent.left = successor.right;
successor.right = temp.right;
successor.right.parent = successor;
}
if(temp == root){
succesor.parent = null;
root = succesor;
successor.parent = null;
root = successor;
return true;
}
//If you're not deleting the root
else{
succesor.parent = temp.parent;
successor.parent = temp.parent;
//This if/else assigns the new node to be either the left or right child of the parent
if(temp.parent.data < temp.data)
temp.parent.right = succesor;
temp.parent.right = successor;
else
temp.parent.left = succesor;
temp.parent.left = successor;
return true;
}
}
@ -148,8 +201,14 @@ class Tree{
}
}
//Move right once and go left down the tree as far as you can
public Node findSuccesor(Node n){
/**
* This method finds the Successor to the Node given.
* Move right once and go left down the tree as far as you can
*
* @param n Node that you want to find the Successor of
* @return The Successor of the node
*/
public Node findSuccessor(Node n){
if(n.right == null)
return n;
Node current = n.right;
@ -161,11 +220,20 @@ class Tree{
return parent;
}
/**
* Returns the root of the Binary Tree
*
* @return the root of the Binary Tree
*/
public Node getRoot(){
return root;
}
//Prints leftChild - root - rightChild
/**
* Prints leftChild - root - rightChild
*
* @param localRoot The local root of the binary tree
*/
public void inOrder(Node localRoot){
if(localRoot != null){
inOrder(localRoot.left);
@ -173,7 +241,12 @@ class Tree{
inOrder(localRoot.right);
}
}
//Prints root - leftChild - rightChild
/**
* Prints root - leftChild - rightChild
*
* @param localRoot The local root of the binary tree
*/
public void preOrder(Node localRoot){
if(localRoot != null){
System.out.print(localRoot.data + " ");
@ -181,7 +254,12 @@ class Tree{
preOrder(localRoot.right);
}
}
//Prints rightChild - leftChild - root
/**
* Prints rightChild - leftChild - root
*
* @param localRoot The local root of the binary tree
*/
public void postOrder(Node localRoot){
if(localRoot != null){
postOrder(localRoot.left);

109
data_structures/DoublyLinkedList.java
View File

@ -1,19 +1,38 @@
/*
* A linked list is similar to an array, it holds values. However, links in a linked list do not have indexes.
* With a linked list you do not need to predetermine it's size as it grows and shrinks as it is edited.
* This is an example of a double ended, doubly linked list.
* Each link references the next link and the previous one.
/**
* This class implements a DoublyLinkedList. This is done using the classes
* LinkedList and Link.
*
* A linked list is simplar to an array, it holds values. However,
* links in a linked list do not have indees. With a linked list
* you do not need to predetermine it's size as it grows and shrinks
* as it is edited. This is an example of a double ended, doubly
* linked list. Each link references the next link and the previous
* one.
*
* @author Unknown
*
*/
class LinkedList{
private Link head; //Head refers to the front of the list
private Link tail; //Tail refers to the back of the list
public LinkedList(){
class DoublyLinkedList{
/** Head refers to the front of the list */
private Link head;
/** Tail refers to the back of the list */
private Link tail;
/**
* Constructor
*/
public DoublyLinkedList(){
head = null;
tail = null;
}
public void insertHead(int x){ //Insert an element at the head
/**
* Insert an element at the head
*
* @param x Element to be inserted
*/
public void insertHead(int x){
Link newLink = new Link(x); //Create a new link with a value attached to it
if(isEmpty()) //Set the first element added to be the tail
tail = newLink;
@ -23,6 +42,11 @@ class LinkedList{
head = newLink; // newLink(head) <--> oldhead
}
/**
* Insert an element at the tail
*
* @param x Element to be inserted
*/
public void insertTail(int x){
Link newLink = new Link(x);
newLink.next = null; // currentTail(tail) newlink -->
@ -31,7 +55,12 @@ class LinkedList{
tail = newLink; // oldTail <--> newLink(tail) -->
}
public Link deleteHead(){ //Delete the element at the head
/**
* Delete the element at the head
*
* @return The new head
*/
public Link deleteHead(){
Link temp = head;
head = head.next; // oldHead <--> 2ndElement(head)
head.previous = null; // oldHead --> 2ndElement(head) nothing pointing at old head so will be removed
@ -40,6 +69,11 @@ class LinkedList{
return temp;
}
/**
* Delete the element at the tail
*
* @return The new tail
*/
public Link deleteTail(){
Link temp = tail;
tail = tail.previous; // 2ndLast(tail) <--> oldTail --> null
@ -47,6 +81,12 @@ class LinkedList{
return temp;
}
/**
* Delete the element from somewhere in the list
*
* @param x element to be deleted
* @return Link deleted
*/
public Link delete(int x){
Link current = head;
@ -66,6 +106,11 @@ class LinkedList{
return current;
}
/**
* Inserts element and reorders
*
* @param x Element to be added
*/
public void insertOrdered(int x){
Link newLink = new Link(x);
Link current = head;
@ -86,10 +131,18 @@ class LinkedList{
}
}
public boolean isEmpty(){ //Returns true if list is empty
/**
* Returns true if list is empty
*
* @return true if list is empty
*/
public boolean isEmpty(){
return(head == null);
}
/**
* Prints contents of the list
*/
public void display(){ //Prints contents of the list
Link current = head;
while(current!=null){
@ -100,24 +153,44 @@ class LinkedList{
}
}
/**
* This class is used to implement the nodes of the
* linked list.
*
* @author Unknown
*
*/
class Link{
/** Value of node */
public int value;
public Link next; //This points to the link in front of the new link
public Link previous; //This points to the link behind the new link
/** This points to the link in front of the new link */
public Link next;
/** This points to the link behind the new link */
public Link previous;
/**
* Constructor
*
* @param value Value of node
*/
public Link(int value){
this.value = value;
}
/**
* Displays the node
*/
public void displayLink(){
System.out.print(value+" ");
}
}
//Example
public class DoublyLinkedList{
/**
* Main Method
*
* @param args Command line arguments
*/
public static void main(String args[]){
LinkedList myList = new LinkedList();
DoublyLinkedList myList = new DoublyLinkedList();
myList.insertHead(13);
myList.insertHead(7);

75
data_structures/PriorityQueues.java
View File

@ -1,21 +1,40 @@
/*
/**
* This class implements a PriorityQueue.
*
* A priority queue adds elements into positions based on their priority.
* So the most important elements are placed at the front/on the top.
* In this example I give numbers that are bigger, a higher priority.
* Queues in theory have no fixed size but when using an array implementation it does.
* Queues in theory have no fixed size but when using an array
* implementation it does.
*
* @author Unknown
*
*/
class PriorityQueue{
/** The max size of the queue */
private int maxSize;
/** The array for the queue */
private int[] queueArray;
/** How many items are in the queue */
private int nItems;
public PriorityQueue(int size){ //Constructor
/**
* Constructor
*
* @param size Size of the queue
*/
public PriorityQueue(int size){
maxSize = size;
queueArray = new int[size];
nItems = 0;
}
public void insert(int value){ //Inserts an element in it's appropriate place
/**
* Inserts an element in it's appropriate place
*
* @param value Value to be inserted
*/
public void insert(int value){
if(nItems == 0){
queueArray[0] = value;
}
@ -30,28 +49,64 @@ class PriorityQueue{
nItems++;
}
public int remove(){ //Remove the element from the front of the queue
/**
* Remove the element from the front of the queue
*
* @return The element removed
*/
public int remove(){
return queueArray[--nItems];
}
public int peek(){ //Checks what's at the front of the queue
/**
* Checks what's at the front of the queue
*
* @return element at the front of the queue
*/
public int peek(){
return queueArray[nItems-1];
}
public boolean isEmpty(){ //Returns true is the queue is empty
/**
* Returns true if the queue is empty
*
* @return true if the queue is empty
*/
public boolean isEmpty(){
return(nItems == 0);
}
public boolean isFull(){ //Returns true is the queue is full
/**
* Returns true if the queue is full
*
* @return true if the queue is full
*/
public boolean isFull(){
return(nItems == maxSize);
}
public int getSize(){ //Returns the number of elements in the queue
/**
* Returns the number of elements in the queue
*
* @return number of elements in the queue
*/
public int getSize(){
return nItems;
}
}
//Example
/**
* This class implements the PriorityQueue class above.
*
* @author Unknown
*
*/
public class PriorityQueues{
/**
* Main method
*
* @param args Command Line Arguments
*/
public static void main(String args[]){
PriorityQueue myQueue = new PriorityQueue(4);
myQueue.insert(10);

80
data_structures/Queues.java
View File

@ -1,16 +1,31 @@
/*
/**
* This implements Queues by using the class Queue.
*
* A queue data structure functions the same as a real world queue.
* The elements that are added first are the first to be removed.
* New elements are added to the back/rear of the queue.
*
* @author Unknown
*
*/
class Queue{
/** Max size of the queue */
private int maxSize;
/** The array representing the queue */
private int[] queueArray;
/** Front of the queue */
private int front;
/** Rear of the queue */
private int rear;
/** How many items are in the queue */
private int nItems;
public Queue(int size){ //Constructor
/**
* Constructor
*
* @param size Size of the new queue
*/
public Queue(int size){
maxSize = size;
queueArray = new int[size];
front = 0;
@ -18,7 +33,13 @@ class Queue{
nItems = 0;
}
public boolean insert(int x){ //Inserts an element at the rear of the queue
/**
* Inserts an element at the rear of the queue
*
* @param x element to be added
* @return True if the element was added successfully
*/
public boolean insert(int x){
if(isFull())
return false;
if(rear == maxSize-1) //If the back of the queue is the end of the array wrap around to the front
@ -29,6 +50,11 @@ class Queue{
return true;
}
/**
* Remove an element from the front of the queue
*
* @return the new front of the queue
*/
public int remove(){ //Remove an element from the front of the queue
if(isEmpty()){
System.out.println("Queue is empty");
@ -42,28 +68,64 @@ class Queue{
return temp;
}
public int peekFront(){ //Checks what's at the front of the queue
/**
* Checks what's at the front of the queue
*
* @return element at the front of the queue
*/
public int peekFront(){
return queueArray[front];
}
public int peekRear(){ //Checks what's at the rear of the queue
/**
* Checks what's at the rear of the queue
*
* @return element at the rear of the queue
*/
public int peekRear(){
return queueArray[rear];
}
public boolean isEmpty(){ //Returns true is the queue is empty
/**
* Returns true if the queue is empty
*
* @return true if the queue is empty
*/
public boolean isEmpty(){
return(nItems == 0);
}
public boolean isFull(){ //Returns true is the queue is full
/**
* Returns true if the queue is full
*
* @return true if the queue is full
*/
public boolean isFull(){
return(nItems == maxSize);
}
public int getSize(){ //Returns the number of elements in the queue
/**
* Returns the number of elements in the queue
*
* @return number of elements in the queue
*/
public int getSize(){
return nItems;
}
}
//Example
/**
* This class is the example for the Queue class
*
* @author Unknown
*
*/
public class Queues{
/**
* Main method
*
* @param args Command line arguments
*/
public static void main(String args[]){
Queue myQueue = new Queue(4);
myQueue.insert(10);

114
data_structures/SinglyLinkedList.java
View File

@ -1,58 +1,78 @@
/*
* A linked list is similar to an array, it holds values. However, links in a linked list do not have indexes.
* With a linked list you do not need to predetermine it's size as it grows and shrinks as it is edited.
* This is an example of a singly linked list. Elements can only be added/removed at the head/front of the list.
/**
* This class implements a SinglyLinked List. This is done
* using SinglyLinkedList class and a LinkForLinkedList Class.
*
* A linked list is implar to an array, it hold values.
* However, links in a linked list do not have indexes. With
* a linked list you do not need to predetermine it's size as
* it gorws and shrinks as it is edited. This is an example of
* a singly linked list. Elements can only be added/removed
* at the head/front of the list.
*
* @author Unknown
*
*/
class LinkedList{
private Link head; //Head refers to the front of the list
class SinglyLinkedList{
/**Head refered to the front of the list */
private LinkForLinkedList head;
public LinkedList(){
/**
* Constructor of SinglyLinkedList
*/
public SinglyLinkedList(){
head = null;
}
public void insertHead(int x){ //Insert an element at the head
Link newLink = new Link(x); //Create a new link with a value attached to it
/**
* This method inserts an element at the head
*
* @param x Element to be added
*/
public void insertHead(int x){
LinkForLinkedList newLink = new LinkForLinkedList(x); //Create a new link with a value attached to it
newLink.next = head; //Set the new link to point to the current head
head = newLink; //Now set the new link to be the head
}
public Link deleteHead(){ //Delete the element at the head
Link temp = head;
/**
* This method deletes an element at the head
*
* @return The element deleted
*/
public LinkForLinkedList deleteHead(){
LinkForLinkedList temp = head;
head = head.next; //Make the second element in the list the new head, the Java garbage collector will later remove the old head
return temp;
}
public boolean isEmpty(){ //Returns true if list is empty
/**
* Checks if the list is empty
*
* @return true is list is empty
*/
public boolean isEmpty(){
return(head == null);
}
public void display(){ //Prints contents of the list
Link current = head;
/**
* Prints contents of the list
*/
public void display(){
LinkForLinkedList current = head;
while(current!=null){
current.displayLink();
current = current.next;
}
System.out.println();
}
}
class Link{
public int value;
public Link next; //This is what the link will point to
public Link(int valuein){
value = valuein;
}
public void displayLink(){
System.out.print(value+" ");
}
}
//Example
public class SinglyLinkedList{
/**
* Main method
*
* @param args Command line arguments
*/
public static void main(String args[]){
LinkedList myList = new LinkedList();
SinglyLinkedList myList = new SinglyLinkedList();
System.out.println(myList.isEmpty()); //Will print true
@ -67,3 +87,35 @@ public class SinglyLinkedList{
myList.display(); // 7(head) --> 5
}
}
/**
* This class is the nodes of the SinglyLinked List.
* They consist of a vlue and a pointer to the node
* after them.
*
* @author Unknown
*
*/
class LinkForLinkedList{
/** The value of the node */
public int value;
/** Point to the next node */
public LinkForLinkedList next; //This is what the link will point to
/**
* Constructor
*
* @param valuein Value to be put in the node
*/
public LinkForLinkedList(int valuein){
value = valuein;
}
/**
* Prints out the value of the node
*/
public void displayLink(){
System.out.print(value+" ");
}
}

133
data_structures/Stacks.java
View File

@ -1,62 +1,131 @@
/*
*A stack is exactly what it sounds like. An element gets added to top of the stack and only the element on the top may be removed.
*This is an example of an array implementation of a Stack. So an element can only be added/removed from the end of the array.
*In theory stacks have no fixed size, but with an array implementation it does.
import java.util.ArrayList;
/**
* This class implements a Stack using two different implementations.
* Stack is used with a regular array and Stack2 uses an ArrayList.
*
* A stack is exactly what it sounds like. An element gets added to the top of
* the stack and only the element on the top may be removed. This is an example
* of an array implementation of a Stack. So an element can only be added/removed
* from the end of the array. In theory stack have no fixed size, but with an
* array implementation it does.
*
* @author Unknown
*
*/
class Stack{
/** The max size of the Stack */
private int maxSize;
/** The array representation of the Stack */
private int[] stackArray;
/** The top of the stack */
private int top;
public Stack(int size){ //Constructor
/**
* Constructor
*
* @param size Size of the Stack
*/
public Stack(int size){
maxSize = size;
stackArray = new int[maxSize];
top = -1;
}
public void push(int value){ //Adds an element to the top of the stack
/**
* Adds an element to the top of the stack
*
* @param value The element added
*/
public void push(int value){
top++;
stackArray[top] = value;
}
public int pop(){ //Removes the top element of the stack and returns the value you've removed
/**
* Removes the top element of the stack and returns the value you've removed
*
* @return value popped off the Stack
*/
public int pop(){
return stackArray[top--];
}
public int peek(){ //Returns the element at the top of the stack
/**
* Returns the element at the top of the stack
*
* @return element at the top of the stack
*/
public int peek(){
return stackArray[top];
}
public boolean isEmpty(){ //Returns true if the stack is empty
/**
* Returns true if the stack is empty
*
* @return true if the stack is empty
*/
public boolean isEmpty(){
return(top == -1);
}
public boolean isFull(){ //Returns true if the stack is full
/**
* Returns true if the stack is full
*
* @return true if the stack is full
*/
public boolean isFull(){
return(top+1 == maxSize);
}
/**
* Deletes everything in the Stack
*
* Doesn't delete elements in the array
* but if you call push method after calling
* makeEmpty it will overwrite previous
* values
*/
public void makeEmpty(){ //Doesn't delete elements in the array but if you call
top = -1; //push method after calling makeEmpty it will overwrite previous values
}
}
/* This is ArrayList Implementation of stack , Where size is not
a problem we can extend the stack as much as we want*/
/**
* This is an ArrayList Implementation of stack, Where size is not
* a problem we can extend the stack as much as we want.
*
* @author Unknown
*
*/
class Stack2{
/** ArrayList representation of the stack */
ArrayList<Integer> stackList;
Stack2(){ //constructor
/**
* Constructor
*/
Stack2(){
stackList=new ArrayList<>();
}
void push(int value){ //adds value to the end of list which is the top for stack
/**
* Adds value to the end of list which
* is the top for stack
*
* @param value value to be added
*/
void push(int value){
stackList.add(value);
}
int pop(){ //pops last element of list which is indeed the top for Stack
/**
* Pops last element of list which is indeed
* the top for Stack
*
* @return Element popped
*/
int pop(){
if(!isEmpty()){ // checks for an empty Stack
@ -71,7 +140,12 @@ class Stack2{
}
boolean isEmpty(){ //checks for empty Stack
/**
* Checks for empty Stack
*
* @return true if stack is empty
*/
boolean isEmpty(){
if(stackList.isEmpty())
return true;
@ -79,13 +153,28 @@ class Stack2{
}
int peek(){ //top element of stack
/**
* Top element of stack
*
* @return top element of stack
*/
int peek(){
return stackList.get(stackList.size()-1);
}
}
//Example
/**
* This class implements the Stack and Stack2 created above
*
* @author Unknown
*
*/
public class Stacks{
/**
* Main method
*
* @param args Command line arguments
*/
public static void main(String args[]){
Stack myStack = new Stack(4); //Declare a stack of maximum size 4
//Populate the stack

8
data_structures/heaps/MaxHeap.java
View File

@ -84,7 +84,13 @@ public class MaxHeap implements Heap {
@Override
public void deleteElement(int elementIndex) {
if (isempty(maxHeap)) throw new EmptyHeapException("Attempt to delete an element from an empty heap");
if (maxHeap.isEmpty())
try {
throw new EmptyHeapException("Attempt to delete an element from an empty heap");
} catch (EmptyHeapException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if ((elementIndex > maxHeap.size()) && (elementIndex <= 0)) throw new IndexOutOfBoundsException("Index out of heap range");
// The last element in heap replaces the one to be deleted
maxHeap.set(elementIndex - 1, getElement(maxHeap.size()));

8
data_structures/heaps/MinHeap.java
View File

@ -87,7 +87,13 @@ public class MinHeap implements Heap {
@Override
public void deleteElement(int elementIndex) {
if (isempty(maxHeap)) throw new EmptyHeapException("Attempt to delete an element from an empty heap");
if (minHeap.isEmpty())
try {
throw new EmptyHeapException("Attempt to delete an element from an empty heap");
} catch (EmptyHeapException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if ((elementIndex > minHeap.size()) && (elementIndex <= 0)) throw new IndexOutOfBoundsException("Index out of heap range");
// The last element in heap replaces the one to be deleted
minHeap.set(elementIndex - 1, getElement(minHeap.size()));

20
dfs.java
View File

@ -1,8 +1,21 @@
import java.util.*;
public class App{
/**
* Implementation of a Depth First Search
*
* @author Unknown
*
*/
public class dfs{
/**
* Implementation in code of a DFS
*
* @param a structure to be DFS'ed
* @param vertices The vertices
* @param source The source
*/
public static void dfs(byte [][] a,int vertices,int source){ //passing adjacency matrix and no of vertices
byte []b=new byte[vertices]; //flag container containing status of each vertices
Arrays.fill(b,(byte)-1); //status initialization
@ -27,6 +40,11 @@ public class App{
}
/**
* The main method
*
* @param args Command line arguments
*/
public static void main(String args[]){
Scanner in=new Scanner(System.in);
int vertices=in.nextInt(),source=in.nextInt();