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Merge pull request #672 from hayderhassan/separate-stacks-class to fix #667

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Separate stacks class
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Libin Yang 2019-01-06 09:03:13 +08:00 committed by GitHub
commit 8d11e5bb39
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5 changed files with 250 additions and 242 deletions
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152
DataStructures/Stacks/StackArray.java Normal file
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/**
* This class implements a Stack using a regular array.
* <p>
* 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
*/
public class StackArray {
/**
* Main method
*
* @param args Command line arguments
*/
public static void main(String[] args) {
// Declare a stack of maximum size 4
StackArray myStackArray = new StackArray(4);
// Populate the stack
myStackArray.push(5);
myStackArray.push(8);
myStackArray.push(2);
myStackArray.push(9);
System.out.println("*********************Stack Array Implementation*********************");
System.out.println(myStackArray.isEmpty()); // will print false
System.out.println(myStackArray.isFull()); // will print true
System.out.println(myStackArray.peek()); // will print 9
System.out.println(myStackArray.pop()); // will print 9
System.out.println(myStackArray.peek()); // will print 2
}
/**
* 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;
/**
* Constructor
*
* @param size Size of the Stack
*/
public StackArray(int size) {
maxSize = size;
stackArray = new int[maxSize];
top = -1;
}
/**
* Adds an element to the top of the stack
*
* @param value The element added
*/
public void push(int value) {
if (!isFull()) { // Checks for a full stack
top++;
stackArray[top] = value;
} else {
resize(maxSize * 2);
push(value); // don't forget push after resizing
}
}
/**
* Removes the top element of the stack and returns the value you've removed
*
* @return value popped off the Stack
*/
public int pop() {
if (!isEmpty()) { // Checks for an empty stack
return stackArray[top--];
}
if (top < maxSize / 4) {
resize(maxSize / 2);
return pop();// don't forget pop after resizing
} else {
System.out.println("The stack is already empty");
return -1;
}
}
/**
* Returns the element at the top of the stack
*
* @return element at the top of the stack
*/
public int peek() {
if (!isEmpty()) { // Checks for an empty stack
return stackArray[top];
} else {
System.out.println("The stack is empty, cant peek");
return -1;
}
}
private void resize(int newSize) {
// private int[] transferArray = new int[newSize]; we can't put modifiers here !
int[] transferArray = new int[newSize];
// for(int i = 0; i < stackArray.length(); i++){ the length isn't a method .
for (int i = 0; i < stackArray.length; i++) {
transferArray[i] = stackArray[i];
stackArray = transferArray;
}
maxSize = newSize;
}
/**
* Returns true if the stack is empty
*
* @return true if the stack is empty
*/
public boolean isEmpty() {
return (top == -1);
}
/**
* 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
* <p>
* 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
}
}

95
DataStructures/Stacks/StackArrayList.java Normal file
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import java.util.ArrayList;
/**
* This class implements a Stack using an ArrayList.
* <p>
* 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.
* <p>
* This is an ArrayList Implementation of a stack, where size is not
* a problem we can extend the stack as much as we want.
*
* @author Unknown
*/
public class StackArrayList {
/**
* Main method
*
* @param args Command line arguments
*/
public static void main(String[] args) {
StackArrayList myStackArrayList = new StackArrayList();
myStackArrayList.push(5);
myStackArrayList.push(8);
myStackArrayList.push(2);
myStackArrayList.push(9);
System.out.println("*********************Stack List Implementation*********************");
System.out.println(myStackArrayList.isEmpty()); // will print false
System.out.println(myStackArrayList.peek()); // will print 9
System.out.println(myStackArrayList.pop()); // will print 9
System.out.println(myStackArrayList.peek()); // will print 2
System.out.println(myStackArrayList.pop()); // will print 2
}
/**
* ArrayList representation of the stack
*/
private ArrayList<Integer> stackList;
/**
* Constructor
*/
public StackArrayList() {
stackList = new ArrayList<>();
}
/**
* Adds value to the end of list which
* is the top for stack
*
* @param value value to be added
*/
public void push(int value) {
stackList.add(value);
}
/**
* Pops last element of list which is indeed
* the top for Stack
*
* @return Element popped
*/
public int pop() {
if (!isEmpty()) { // checks for an empty Stack
int popValue = stackList.get(stackList.size() - 1);
stackList.remove(stackList.size() - 1); // removes the poped element from the list
return popValue;
}
System.out.print("The stack is already empty!");
return -1;
}
/**
* Checks for empty Stack
*
* @return true if stack is empty
*/
public boolean isEmpty() {
return stackList.isEmpty();
}
/**
* Top element of stack
*
* @return top element of stack
*/
public int peek() {
return stackList.get(stackList.size() - 1);
}
}

240
DataStructures/Stacks/Stacks.java
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@ -1,240 +0,0 @@
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;
/**
* Constructor
*
* @param size Size of the Stack
*/
public Stack(int size){
maxSize = size;
stackArray = new int[maxSize];
top = -1;
}
/**
* Adds an element to the top of the stack
*
* @param value The element added
*/
public void push(int value){
if(!isFull()){ //Checks for a full stack
top++;
stackArray[top] = value;
}else{
resize(maxSize*2);
push(value);// don't forget push after resizing
}
}
/**
* Removes the top element of the stack and returns the value you've removed
*
* @return value popped off the Stack
*/
public int pop(){
if(!isEmpty()){ //Checks for an empty stack
return stackArray[top--];
}
if(top < maxSize/4){
resize(maxSize/2);
return pop();// don't forget pop after resizing
}
else{
System.out.println("The stack is already empty");
return -1;
}
}
/**
* Returns the element at the top of the stack
*
* @return element at the top of the stack
*/
public int peek(){
if(!isEmpty()){ //Checks for an empty stack
return stackArray[top];
}else{
System.out.println("The stack is empty, cant peek");
return -1;
}
}
private void resize(int newSize){
//private int[] transferArray = new int[newSize]; we can't put modifires here !
int[] transferArray = new int[newSize];
//for(int i = 0; i < stackArray.length(); i++){ the length isn't a method .
for(int i = 0; i < stackArray.length; i++){
transferArray[i] = stackArray[i];
stackArray = transferArray;
}
maxSize = newSize;
}
/**
* Returns true if the stack is empty
*
* @return true if the stack is empty
*/
public boolean isEmpty(){
return(top == -1);
}
/**
* 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 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;
/**
* Constructor
*/
Stack2(){
stackList=new ArrayList<>();
}
/**
* 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);
}
/**
* Pops last element of list which is indeed
* the top for Stack
*
* @return Element popped
*/
int pop(){
if(!isEmpty()){ // checks for an empty Stack
int popValue=stackList.get(stackList.size()-1);
stackList.remove(stackList.size()-1); //removes the poped element from the list
return popValue;
}
else{
System.out.print("The stack is already empty ");
return -1;
}
}
/**
* Checks for empty Stack
*
* @return true if stack is empty
*/
boolean isEmpty(){
if(stackList.isEmpty())
return true;
else return false;
}
/**
* Top element of stack
*
* @return top element of stack
*/
int peek(){
return stackList.get(stackList.size()-1);
}
}
/**
* 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
myStack.push(5);
myStack.push(8);
myStack.push(2);
myStack.push(9);
System.out.println("*********************Stack Array Implementation*********************");
System.out.println(myStack.isEmpty()); //will print false
System.out.println(myStack.isFull()); //will print true
System.out.println(myStack.peek()); //will print 9
System.out.println(myStack.pop()); //will print 9
System.out.println(myStack.peek()); // will print 2
Stack2 myStack2 = new Stack2(); //Declare a stack of maximum size 4
//Populate the stack
myStack2.push(5);
myStack2.push(8);
myStack2.push(2);
myStack2.push(9);
System.out.println("*********************Stack List Implementation*********************");
System.out.println(myStack2.isEmpty()); //will print false
System.out.println(myStack2.peek()); //will print 9
System.out.println(myStack2.pop()); //will print 9
System.out.println(myStack2.peek()); // will print 2
System.out.println(myStack2.pop()); //will print 2
}
}

2
README-ko.md
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@ -179,7 +179,7 @@ and much more...| and more...
------|-----|
[노드 스택](DataStructures/Stacks/NodeStack.java)|[AVL 트리](DataStructures/Trees/AVLTree.java)|
[연결리스트 스택](DataStructures/Stacks/StackOfLinkedList.java)|[이진 트리](DataStructures/Trees/BinaryTree.java)|
[스택](DataStructures/Stacks/Stacks.java)|And much more...|
[스택](DataStructures/Stacks)|And much more...|
* [Bags](DataStructures/Bags/Bag.java)
* [Buffer](DataStructures/Buffers/CircularBuffer.java)

3
README.md
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@ -181,7 +181,8 @@ Stacks|Trees|
------|-----|
[Node Stack](DataStructures/Stacks/NodeStack.java)|[AVL Tree](DataStructures/Trees/AVLTree.java)|
[Stack of Linked List](DataStructures/Stacks/StackOfLinkedList.java)|[Binary Tree](DataStructures/Trees/BinaryTree.java)|
[Stacks](DataStructures/Stacks/Stacks.java)|And much more...|
[Array Stack](DataStructures/Stacks/StackArray.java)|And much more...|
[ArrayList Stack](DataStructures/Stacks/StackArrayList.java)||
* [Bags](DataStructures/Bags/Bag.java)
* [Buffer](DataStructures/Buffers/CircularBuffer.java)