Improved files and folders name conventions and moved lost files to Misc folder

Data Structures/HashMap/HashMap.java

@@ -1,141 +1,141 @@
-
-
-import java.util.ArrayList;
-import java.util.LinkedList;
-
-public class HashMap<K,V> {
-	public class hmnodes{ //HashMap nodes 
-		K key;
-		V value;
-	}
-	
-	private int size=0; //size of hashmap
-	private LinkedList<hmnodes> buckets[];  //array of addresses of list
-	
-	public HashMap(){
-		buckets=new LinkedList[4]; //initially create bucket of any size 
-		for(int i=0;i<4;i++)
-			buckets[i]=new LinkedList<>(); 
-	}
-	
-	public void put(K key,V value) throws Exception{
-		int bi=bucketIndex(key); //find the index,the new key will be inserted in linklist at that index
-		int fountAt=find(bi,key); //check if key already exists or not 
-		if(fountAt==-1){
-			hmnodes temp=new hmnodes(); //if doesn't exist create new node and insert 
-			temp.key=key;
-			temp.value=value;
-			buckets[bi].addLast(temp);
-			this.size++;
-		}else{
-			buckets[bi].get(fountAt).value=value;//if already exist modify the value
-		}
-		
-		double lambda = (this.size*1.0)/this.buckets.length;
-		if(lambda>2.0){
-			rehash();  //rehashing function which will increase the size of bucket as soon as lambda exceeds 2.0
-		}
-		
-		return;
-	}
-	
-
-	public V get(K key) throws Exception{
-		int bi=bucketIndex(key);
-		int fountAt=find(bi,key);
-		if(fountAt==-1){
-			return null;
-		}else{
-			return buckets[bi].get(fountAt).value;
-		}
-	}
-	
-	public V remove(K key) throws Exception{
-		int bi=bucketIndex(key);
-		int fountAt=find(bi,key);
-		if(fountAt==-1){
-			return null;
-		}else{
-			this.size--;
-			return buckets[bi].remove(fountAt).value;
-		}
-	}
-	
-	public boolean containskey(K key) throws Exception{
-		int bi=bucketIndex(key);
-		int fountAt=find(bi,key);
-		if(fountAt==-1){
-			return false;
-		}else{
-			return true;
-		}
-	}
-	
-	public int size(){
-		return this.size;
-	}
-	
-	
-	public boolean isempty(){
-		return this.size==0;
-	}
-	
-	public ArrayList<K> keyset() throws Exception{
-		ArrayList<K> arr=new ArrayList<>();
-		for(int i=0;i<buckets.length;i++){
-			for(int j=0;j<buckets[i].size();j++){
-				arr.add(buckets[i].get(j).key);
-			}
-		}
-		return arr;
-	}
-	
-	public ArrayList<V> valueset() throws Exception{
-		ArrayList<V> arr=new ArrayList<>();
-		for(int i=0;i<buckets.length;i++){
-			for(int j=0;j<buckets[i].size();j++){
-				arr.add(buckets[i].get(j).value);
-			}
-		}
-		return arr;
-	}
-	
-	public void display() throws Exception{
-		for(int i=0;i<buckets.length;i++){
-			System.out.print("Bucket: "+i+" ");
-			for(int j=0;j<buckets[i].size();j++){
-				hmnodes temp=buckets[i].get(j);
-				System.out.print("["+temp.key+"->"+temp.value+"]");
-			}
-			System.out.println();
-		}
-	}
-	
-	public int find(int bi,K key) throws Exception{
-		for(int i=0;i<buckets[bi].size();i++){
-			if(key.equals(buckets[bi].get(i).key))
-				return i;
-		}
-		return -1;
-	}
-	
-	public int bucketIndex(K key) throws Exception{
-		int bi=key.hashCode();
-		return Math.abs(bi%buckets.length);
-	}
-
-	private void rehash() throws Exception{
-		LinkedList<hmnodes> ob[]= buckets;
-		buckets=new LinkedList[ob.length*2];
-		for(int i=0;i<ob.length*2;i++)
-			buckets[i]=new LinkedList<>();
-		
-		size = 0;
-		for(int i=0;i<ob.length;i++){
-			for(int j=0;j<ob[i].size();j++){
-				put(ob[i].get(j).key,ob[i].get(j).value);
-			}
-		}
-		
-	}
-}
+
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+
+public class HashMap<K,V> {
+	public class hmnodes{ //HashMap nodes 
+		K key;
+		V value;
+	}
+	
+	private int size=0; //size of hashmap
+	private LinkedList<hmnodes> buckets[];  //array of addresses of list
+	
+	public HashMap(){
+		buckets=new LinkedList[4]; //initially create bucket of any size 
+		for(int i=0;i<4;i++)
+			buckets[i]=new LinkedList<>(); 
+	}
+	
+	public void put(K key,V value) throws Exception{
+		int bi=bucketIndex(key); //find the index,the new key will be inserted in linklist at that index
+		int fountAt=find(bi,key); //check if key already exists or not 
+		if(fountAt==-1){
+			hmnodes temp=new hmnodes(); //if doesn't exist create new node and insert 
+			temp.key=key;
+			temp.value=value;
+			buckets[bi].addLast(temp);
+			this.size++;
+		}else{
+			buckets[bi].get(fountAt).value=value;//if already exist modify the value
+		}
+		
+		double lambda = (this.size*1.0)/this.buckets.length;
+		if(lambda>2.0){
+			rehash();  //rehashing function which will increase the size of bucket as soon as lambda exceeds 2.0
+		}
+		
+		return;
+	}
+	
+
+	public V get(K key) throws Exception{
+		int bi=bucketIndex(key);
+		int fountAt=find(bi,key);
+		if(fountAt==-1){
+			return null;
+		}else{
+			return buckets[bi].get(fountAt).value;
+		}
+	}
+	
+	public V remove(K key) throws Exception{
+		int bi=bucketIndex(key);
+		int fountAt=find(bi,key);
+		if(fountAt==-1){
+			return null;
+		}else{
+			this.size--;
+			return buckets[bi].remove(fountAt).value;
+		}
+	}
+	
+	public boolean containskey(K key) throws Exception{
+		int bi=bucketIndex(key);
+		int fountAt=find(bi,key);
+		if(fountAt==-1){
+			return false;
+		}else{
+			return true;
+		}
+	}
+	
+	public int size(){
+		return this.size;
+	}
+	
+	
+	public boolean isempty(){
+		return this.size==0;
+	}
+	
+	public ArrayList<K> keyset() throws Exception{
+		ArrayList<K> arr=new ArrayList<>();
+		for(int i=0;i<buckets.length;i++){
+			for(int j=0;j<buckets[i].size();j++){
+				arr.add(buckets[i].get(j).key);
+			}
+		}
+		return arr;
+	}
+	
+	public ArrayList<V> valueset() throws Exception{
+		ArrayList<V> arr=new ArrayList<>();
+		for(int i=0;i<buckets.length;i++){
+			for(int j=0;j<buckets[i].size();j++){
+				arr.add(buckets[i].get(j).value);
+			}
+		}
+		return arr;
+	}
+	
+	public void display() throws Exception{
+		for(int i=0;i<buckets.length;i++){
+			System.out.print("Bucket: "+i+" ");
+			for(int j=0;j<buckets[i].size();j++){
+				hmnodes temp=buckets[i].get(j);
+				System.out.print("["+temp.key+"->"+temp.value+"]");
+			}
+			System.out.println();
+		}
+	}
+	
+	public int find(int bi,K key) throws Exception{
+		for(int i=0;i<buckets[bi].size();i++){
+			if(key.equals(buckets[bi].get(i).key))
+				return i;
+		}
+		return -1;
+	}
+	
+	public int bucketIndex(K key) throws Exception{
+		int bi=key.hashCode();
+		return Math.abs(bi%buckets.length);
+	}
+
+	private void rehash() throws Exception{
+		LinkedList<hmnodes> ob[]= buckets;
+		buckets=new LinkedList[ob.length*2];
+		for(int i=0;i<ob.length*2;i++)
+			buckets[i]=new LinkedList<>();
+		
+		size = 0;
+		for(int i=0;i<ob.length;i++){
+			for(int j=0;j<ob[i].size();j++){
+				put(ob[i].get(j).key,ob[i].get(j).value);
+			}
+		}
+		
+	}
+}

Data Structures/Trees/GenericTree.Java

@@ -1,226 +1,226 @@
-import java.util.ArrayList;
-import java.util.LinkedList;
-import java.util.Scanner;
-
-public class treeclass {
-	private class Node {
-		int data;
-		ArrayList<Node> child = new ArrayList<>();
-	}
-
-	private Node root;
-	private int size;
-
-	/*
-	A generic tree is a tree which can have as many children as it can be
-	It might be possible that every node present is directly connected to
-	root node.
-
-	In this code
-	Every function has two copies: one function is helper function which can be called from
-	main and from that function a private function is called which will do the actual work.
-	I have done this, while calling from main one have to give minimum parameters.
-
-	*/
-	public treeclass() {     //Constructor
-		Scanner scn = new Scanner(System.in);
-		root = create_treeG(null, 0, scn);
-	}
-
-	private Node create_treeG(Node node, int childindx, Scanner scn) {
-		// display
-		if (node == null) {
-			System.out.println("Enter root's data");
-		} else {
-			System.out.println("Enter data of parent of index " + node.data + " " + childindx);
-		}
-		// input
-		node = new Node();
-		node.data = scn.nextInt();
-		System.out.println("number of children");
-		int number = scn.nextInt();
-		for (int i = 0; i < number; i++) {
-			Node childd = create_treeG(node, i, scn);
-			size++;
-			node.child.add(childd);
-		}
-		return node;
-	}
-
-	/*
-	Function to display the generic tree
-	*/
-	public void display() {  //Helper function
-		display_1(root);
-		return;
-	}
-
-	private void display_1(Node parent) {
-		System.out.print(parent.data + "=>");
-		for (int i = 0; i < parent.child.size(); i++) {
-			System.out.print(parent.child.get(i).data + " ");
-		}
-		System.out.println(".");
-		for (int i = 0; i < parent.child.size(); i++) {
-			display_1(parent.child.get(i));
-		}
-		return;
-	}
-
-	/*
-	 One call store the size directly but if you are asked compute size this function to calcuate
-	 size goes as follows
-	 */
-
-	public int size2call() {
-		return size2(root);
-	}
-
-	public int size2(Node roott) {
-		int sz = 0;
-		for (int i = 0; i < roott.child.size(); i++) {
-			sz += size2(roott.child.get(i));
-		}
-		return sz + 1;
-	}
-
-	/*
-	Function to compute maximum value in the generic tree
-	*/
-	public int maxcall() {
-		int maxi = root.data;
-		return max(root, maxi);
-	}
-
-	private int max(Node roott, int maxi) {
-		if (maxi < roott.data)
-			maxi = roott.data;
-		for (int i = 0; i < roott.child.size(); i++) {
-			maxi = max(roott.child.get(i), maxi);
-		}
-
-		return maxi;
-	}
-
-	/*
-	Function to compute HEIGHT of the generic tree
-	*/
-
-	public int heightcall() {
-		return height(root) - 1;
-	}
-
-	private int height(Node node) {
-		int h = 0;
-		for (int i = 0; i < node.child.size(); i++) {
-			int k = height(node.child.get(i));
-			if (k > h)
-				h = k;
-		}
-		return h + 1;
-	}
-
-	/*
-	Function to find whether a number is present in the generic tree or not
-	*/
-
-	public boolean findcall(int info) {
-		return find(root, info);
-	}
-
-	private boolean find(Node node, int info) {
-		if (node.data == info)
-			return true;
-		for (int i = 0; i < node.child.size(); i++) {
-			if (find(node.child.get(i), info))
-				return true;
-		}
-		return false;
-	}
-
-	/*
-	Function to calculate depth of generic tree
-	*/
-	public void depthcaller(int dep) {
-		depth(root, dep);
-	}
-
-	public void depth(Node node, int dep) {
-		if (dep == 0) {
-			System.out.println(node.data);
-			return;
-		}
-		for (int i = 0; i < node.child.size(); i++)
-			depth(node.child.get(i), dep - 1);
-		return;
-	}
-
-	/*
-	Function to print generic tree in pre-order
-	*/
-	public void preordercall() {
-		preorder(root);
-		System.out.println(".");
-	}
-
-	private void preorder(Node node) {
-		System.out.print(node.data + " ");
-		for (int i = 0; i < node.child.size(); i++)
-			preorder(node.child.get(i));
-	}
-
-	/*
-	Function to print generic tree in post-order
-	*/
-	public void postordercall() {
-		postorder(root);
-		System.out.println(".");
-	}
-
-	private void postorder(Node node) {
-		for (int i = 0; i < node.child.size(); i++)
-			postorder(node.child.get(i));
-		System.out.print(node.data + " ");
-	}
-
-	/*
-	Function to print generic tree in level-order
-	*/
-
-	public void levelorder() {
-		LinkedList<Node> q = new LinkedList<>();
-		q.addLast(root);
-		while (!q.isEmpty()) {
-			int k = q.getFirst().data;
-			System.out.print(k + " ");
-
-			for (int i = 0; i < q.getFirst().child.size(); i++) {
-				q.addLast(q.getFirst().child.get(i));
-			}
-			q.removeFirst();
-		}
-		System.out.println(".");
-	}
-
-	/*
-	 Function to remove all leaves of generic tree
-	 */
-	public void removeleavescall() {
-		removeleaves(root);
-	}
-
-	private void removeleaves(Node node) {
-		ArrayList<Integer> arr = new ArrayList<>();
-		for (int i = 0; i < node.child.size(); i++) {
-			if (node.child.get(i).child.size() == 0) {
-				arr.add(i);
-				// node.child.remove(i);
-				// i--;
-			} else
-				removeleaves(node.child.get(i));
-		}
-		for (int i = arr.size() - 1; i >= 0; i--) {
-			node.child.remove(arr.get(i) + 0);
-		}
-	}
-
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.Scanner;
+
+public class treeclass {
+	private class Node {
+		int data;
+		ArrayList<Node> child = new ArrayList<>();
+	}
+
+	private Node root;
+	private int size;
+
+	/*
+	A generic tree is a tree which can have as many children as it can be
+	It might be possible that every node present is directly connected to
+	root node.
+
+	In this code
+	Every function has two copies: one function is helper function which can be called from
+	main and from that function a private function is called which will do the actual work.
+	I have done this, while calling from main one have to give minimum parameters.
+
+	*/
+	public treeclass() {     //Constructor
+		Scanner scn = new Scanner(System.in);
+		root = create_treeG(null, 0, scn);
+	}
+
+	private Node create_treeG(Node node, int childindx, Scanner scn) {
+		// display
+		if (node == null) {
+			System.out.println("Enter root's data");
+		} else {
+			System.out.println("Enter data of parent of index " + node.data + " " + childindx);
+		}
+		// input
+		node = new Node();
+		node.data = scn.nextInt();
+		System.out.println("number of children");
+		int number = scn.nextInt();
+		for (int i = 0; i < number; i++) {
+			Node childd = create_treeG(node, i, scn);
+			size++;
+			node.child.add(childd);
+		}
+		return node;
+	}
+
+	/*
+	Function to display the generic tree
+	*/
+	public void display() {  //Helper function
+		display_1(root);
+		return;
+	}
+
+	private void display_1(Node parent) {
+		System.out.print(parent.data + "=>");
+		for (int i = 0; i < parent.child.size(); i++) {
+			System.out.print(parent.child.get(i).data + " ");
+		}
+		System.out.println(".");
+		for (int i = 0; i < parent.child.size(); i++) {
+			display_1(parent.child.get(i));
+		}
+		return;
+	}
+
+	/*
+	 One call store the size directly but if you are asked compute size this function to calcuate
+	 size goes as follows
+	 */
+
+	public int size2call() {
+		return size2(root);
+	}
+
+	public int size2(Node roott) {
+		int sz = 0;
+		for (int i = 0; i < roott.child.size(); i++) {
+			sz += size2(roott.child.get(i));
+		}
+		return sz + 1;
+	}
+
+	/*
+	Function to compute maximum value in the generic tree
+	*/
+	public int maxcall() {
+		int maxi = root.data;
+		return max(root, maxi);
+	}
+
+	private int max(Node roott, int maxi) {
+		if (maxi < roott.data)
+			maxi = roott.data;
+		for (int i = 0; i < roott.child.size(); i++) {
+			maxi = max(roott.child.get(i), maxi);
+		}
+
+		return maxi;
+	}
+
+	/*
+	Function to compute HEIGHT of the generic tree
+	*/
+
+	public int heightcall() {
+		return height(root) - 1;
+	}
+
+	private int height(Node node) {
+		int h = 0;
+		for (int i = 0; i < node.child.size(); i++) {
+			int k = height(node.child.get(i));
+			if (k > h)
+				h = k;
+		}
+		return h + 1;
+	}
+
+	/*
+	Function to find whether a number is present in the generic tree or not
+	*/
+
+	public boolean findcall(int info) {
+		return find(root, info);
+	}
+
+	private boolean find(Node node, int info) {
+		if (node.data == info)
+			return true;
+		for (int i = 0; i < node.child.size(); i++) {
+			if (find(node.child.get(i), info))
+				return true;
+		}
+		return false;
+	}
+
+	/*
+	Function to calculate depth of generic tree
+	*/
+	public void depthcaller(int dep) {
+		depth(root, dep);
+	}
+
+	public void depth(Node node, int dep) {
+		if (dep == 0) {
+			System.out.println(node.data);
+			return;
+		}
+		for (int i = 0; i < node.child.size(); i++)
+			depth(node.child.get(i), dep - 1);
+		return;
+	}
+
+	/*
+	Function to print generic tree in pre-order
+	*/
+	public void preordercall() {
+		preorder(root);
+		System.out.println(".");
+	}
+
+	private void preorder(Node node) {
+		System.out.print(node.data + " ");
+		for (int i = 0; i < node.child.size(); i++)
+			preorder(node.child.get(i));
+	}
+
+	/*
+	Function to print generic tree in post-order
+	*/
+	public void postordercall() {
+		postorder(root);
+		System.out.println(".");
+	}
+
+	private void postorder(Node node) {
+		for (int i = 0; i < node.child.size(); i++)
+			postorder(node.child.get(i));
+		System.out.print(node.data + " ");
+	}
+
+	/*
+	Function to print generic tree in level-order
+	*/
+
+	public void levelorder() {
+		LinkedList<Node> q = new LinkedList<>();
+		q.addLast(root);
+		while (!q.isEmpty()) {
+			int k = q.getFirst().data;
+			System.out.print(k + " ");
+
+			for (int i = 0; i < q.getFirst().child.size(); i++) {
+				q.addLast(q.getFirst().child.get(i));
+			}
+			q.removeFirst();
+		}
+		System.out.println(".");
+	}
+
+	/*
+	 Function to remove all leaves of generic tree
+	 */
+	public void removeleavescall() {
+		removeleaves(root);
+	}
+
+	private void removeleaves(Node node) {
+		ArrayList<Integer> arr = new ArrayList<>();
+		for (int i = 0; i < node.child.size(); i++) {
+			if (node.child.get(i).child.size() == 0) {
+				arr.add(i);
+				// node.child.remove(i);
+				// i--;
+			} else
+				removeleaves(node.child.get(i));
+		}
+		for (int i = arr.size() - 1; i >= 0; i--) {
+			node.child.remove(arr.get(i) + 0);
+		}
+	}
+

Misc/Huffman.java

@@ -1,158 +1,158 @@
-
-import java.util.Comparator;
-import java.util.Iterator;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Scanner;
-import java.util.Stack;
-/**
- *
- * @author Mayank Kumar (mk9440)
- */
-/*
-Output :
-
-Enter number of distinct letters 
-6
-Enter letters with its frequncy to encode
-Enter letter : a
-Enter frequncy : 45
-
-Enter letter : b
-Enter frequncy : 13
-
-Enter letter : c
-Enter frequncy : 12
-
-Enter letter : d
-Enter frequncy : 16
-
-Enter letter : e
-Enter frequncy : 9
-
-Enter letter : f
-Enter frequncy : 5
-
-Letter		Encoded Form
-a		0 
-b		1 0 1 
-c		1 0 0 
-d		1 1 1 
-e		1 1 0 1 
-f		1 1 0 0 
-
-*/
-
-class Node{
-String letr="";    
-int freq=0,data=0;
-Node left=null,right=null;
-}
-
-//A comparator class to sort list on the basis of their frequency
-class comp implements Comparator<Node>{
- @Override
-    public int compare(Node o1, Node o2) {
-        if(o1.freq>o2.freq){return 1;}
-        else if(o1.freq<o2.freq){return -1;}
-        else{return 0;}
-    }
-}
-
-
-public class Huffman {
-    
-    // A simple function to print a given list
-    //I just made it for debugging
-    public static void print_list(List li){
-    Iterator<Node> it=li.iterator();
-    while(it.hasNext()){Node n=it.next();System.out.print(n.freq+" ");}System.out.println();
-    }
-    
-    //Function for making tree (Huffman Tree)
-    public static Node make_huffmann_tree(List li){
-    //Sorting list in increasing order of its letter frequency    
-    li.sort(new comp());
-    Node temp=null;
-    Iterator it=li.iterator();
-    //System.out.println(li.size());
-    //Loop for making huffman tree till only single node remains in list
-    while(true){
-    temp=new Node();
-    //a and b are  Node which are to be combine to make its parent
-    Node a=new Node(),b=new Node();
-    a=null;b=null;
-    //checking if list is eligible for combining or not
-    //here first assignment of it.next in a will always be true as list till end will
-    //must have atleast one node
-    a=(Node)it.next();
-    //Below condition is to check either list has 2nd node or not to combine 
-    //If this condition will be false, then it means construction of huffman tree is completed
-    if(it.hasNext()){b=(Node)it.next();}
-    //Combining first two smallest nodes in list to make its parent whose frequncy 
-    //will be equals to sum of frequency of these two nodes 
-    if(b!=null){
-    temp.freq=a.freq+b.freq;a.data=0;b.data=1;//assigining 0 and 1 to left and right nodes
-    temp.left=a;temp.right=b;
-    //after combing, removing first two nodes in list which are already combined
-    li.remove(0);//removes first element which is now combined  -step1
-    li.remove(0);//removes 2nd element which comes on 1st position after deleting first in step1
-    li.add(temp);//adding new combined node to list
-    //print_list(li);  //For visualizing each combination step
-    }
-    //Sorting after combining to again repeat above on sorted frequency list
-    li.sort(new comp());    
-    it=li.iterator();//resetting list pointer to first node (head/root of tree)
-    if(li.size()==1){return (Node)it.next();} //base condition ,returning root of huffman tree    
-    }
-}
-    
-    //Function for finding path between root and given letter ch
-    public static void dfs(Node n,String ch){
-        Stack<Node> st=new Stack(); // stack for storing path
-        int freq=n.freq; // recording root freq to avoid it adding in path encoding
-        find_path_and_encode(st,n,ch,freq);
-    }
-    
-    //A simple utility function to print stack (Used for printing path)
-    public static void print_path(Stack<Node> st){
-    for(int i=0;i<st.size();i++){
-    System.out.print(st.elementAt(i).data+" ");
-    }
-    }
-    
-    public static void find_path_and_encode(Stack<Node> st,Node root,String s,int f){
-    //Base condition
-    if(root!= null){
-    if(root.freq!=f){st.push(root);} // avoiding root to add in path/encoding bits
-    if(root.letr.equals(s)){print_path(st);return;} // Recursion stopping condition when path gets founded
-    find_path_and_encode(st,root.left,s,f);
-    find_path_and_encode(st,root.right,s,f); 
-    //Popping if path not found in right or left of this node,because we previously 
-    //pushed this node in taking a mindset that it might be in path
-    st.pop();    
-    }    
-    }
-    
-    public static void main(String args[]){
-    List <Node> li=new LinkedList<>();
-    Scanner in=new Scanner(System.in);
-    System.out.println("Enter number of distinct letters ");
-    int n=in.nextInt();
-    String s[]=new String[n];
-    System.out.print("Enter letters with its frequncy to encode\n");
-    for(int  i=0;i<n;i++){
-    Node a=new Node();
-    System.out.print("Enter letter : ");
-    a.letr=in.next();s[i]=a.letr;
-    System.out.print("Enter frequncy : ");
-    a.freq=in.nextInt();System.out.println();
-    li.add(a);
-    }
-    Node root=new Node();
-    root=make_huffmann_tree(li);
-    System.out.println("Letter\t\tEncoded Form");
-    for(int i=0;i<n;i++){
-    System.out.print(s[i]+"\t\t");dfs(root,s[i]);System.out.println();}
-     }
-}
+
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Scanner;
+import java.util.Stack;
+/**
+ *
+ * @author Mayank Kumar (mk9440)
+ */
+/*
+Output :
+
+Enter number of distinct letters 
+6
+Enter letters with its frequncy to encode
+Enter letter : a
+Enter frequncy : 45
+
+Enter letter : b
+Enter frequncy : 13
+
+Enter letter : c
+Enter frequncy : 12
+
+Enter letter : d
+Enter frequncy : 16
+
+Enter letter : e
+Enter frequncy : 9
+
+Enter letter : f
+Enter frequncy : 5
+
+Letter		Encoded Form
+a		0 
+b		1 0 1 
+c		1 0 0 
+d		1 1 1 
+e		1 1 0 1 
+f		1 1 0 0 
+
+*/
+
+class Node{
+String letr="";    
+int freq=0,data=0;
+Node left=null,right=null;
+}
+
+//A comparator class to sort list on the basis of their frequency
+class comp implements Comparator<Node>{
+ @Override
+    public int compare(Node o1, Node o2) {
+        if(o1.freq>o2.freq){return 1;}
+        else if(o1.freq<o2.freq){return -1;}
+        else{return 0;}
+    }
+}
+
+
+public class Huffman {
+    
+    // A simple function to print a given list
+    //I just made it for debugging
+    public static void print_list(List li){
+    Iterator<Node> it=li.iterator();
+    while(it.hasNext()){Node n=it.next();System.out.print(n.freq+" ");}System.out.println();
+    }
+    
+    //Function for making tree (Huffman Tree)
+    public static Node make_huffmann_tree(List li){
+    //Sorting list in increasing order of its letter frequency    
+    li.sort(new comp());
+    Node temp=null;
+    Iterator it=li.iterator();
+    //System.out.println(li.size());
+    //Loop for making huffman tree till only single node remains in list
+    while(true){
+    temp=new Node();
+    //a and b are  Node which are to be combine to make its parent
+    Node a=new Node(),b=new Node();
+    a=null;b=null;
+    //checking if list is eligible for combining or not
+    //here first assignment of it.next in a will always be true as list till end will
+    //must have atleast one node
+    a=(Node)it.next();
+    //Below condition is to check either list has 2nd node or not to combine 
+    //If this condition will be false, then it means construction of huffman tree is completed
+    if(it.hasNext()){b=(Node)it.next();}
+    //Combining first two smallest nodes in list to make its parent whose frequncy 
+    //will be equals to sum of frequency of these two nodes 
+    if(b!=null){
+    temp.freq=a.freq+b.freq;a.data=0;b.data=1;//assigining 0 and 1 to left and right nodes
+    temp.left=a;temp.right=b;
+    //after combing, removing first two nodes in list which are already combined
+    li.remove(0);//removes first element which is now combined  -step1
+    li.remove(0);//removes 2nd element which comes on 1st position after deleting first in step1
+    li.add(temp);//adding new combined node to list
+    //print_list(li);  //For visualizing each combination step
+    }
+    //Sorting after combining to again repeat above on sorted frequency list
+    li.sort(new comp());    
+    it=li.iterator();//resetting list pointer to first node (head/root of tree)
+    if(li.size()==1){return (Node)it.next();} //base condition ,returning root of huffman tree    
+    }
+}
+    
+    //Function for finding path between root and given letter ch
+    public static void dfs(Node n,String ch){
+        Stack<Node> st=new Stack(); // stack for storing path
+        int freq=n.freq; // recording root freq to avoid it adding in path encoding
+        find_path_and_encode(st,n,ch,freq);
+    }
+    
+    //A simple utility function to print stack (Used for printing path)
+    public static void print_path(Stack<Node> st){
+    for(int i=0;i<st.size();i++){
+    System.out.print(st.elementAt(i).data+" ");
+    }
+    }
+    
+    public static void find_path_and_encode(Stack<Node> st,Node root,String s,int f){
+    //Base condition
+    if(root!= null){
+    if(root.freq!=f){st.push(root);} // avoiding root to add in path/encoding bits
+    if(root.letr.equals(s)){print_path(st);return;} // Recursion stopping condition when path gets founded
+    find_path_and_encode(st,root.left,s,f);
+    find_path_and_encode(st,root.right,s,f); 
+    //Popping if path not found in right or left of this node,because we previously 
+    //pushed this node in taking a mindset that it might be in path
+    st.pop();    
+    }    
+    }
+    
+    public static void main(String args[]){
+    List <Node> li=new LinkedList<>();
+    Scanner in=new Scanner(System.in);
+    System.out.println("Enter number of distinct letters ");
+    int n=in.nextInt();
+    String s[]=new String[n];
+    System.out.print("Enter letters with its frequncy to encode\n");
+    for(int  i=0;i<n;i++){
+    Node a=new Node();
+    System.out.print("Enter letter : ");
+    a.letr=in.next();s[i]=a.letr;
+    System.out.print("Enter frequncy : ");
+    a.freq=in.nextInt();System.out.println();
+    li.add(a);
+    }
+    Node root=new Node();
+    root=make_huffmann_tree(li);
+    System.out.println("Letter\t\tEncoded Form");
+    for(int i=0;i<n;i++){
+    System.out.print(s[i]+"\t\t");dfs(root,s[i]);System.out.println();}
+     }
+}