Adding huffman encoding

Author: coderdoze

Greedy Algorithms/Huffman_Encoding/huffman_encoding.c++

@@ -0,0 +1,83 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+//leaf node contains character(data), intermediate nodes contains frequency
+struct node
+{
+    struct node *l;
+    struct node *r;
+    char data; 
+    int freq;
+};
+
+struct compare{
+    bool operator()(struct node *n1,struct node *n2)
+    {
+         return n1->freq>n2->freq;
+    }
+};
+
+void traverse(node *root,string str)
+{
+    if(!root)
+    return ;
+ 
+    if(root->data!='#'){
+     cout<<str<<" ";
+     return;}    
+
+    //append 0 if traverse to left branch of the node otherwise append 1 
+    
+    // if(root->l)
+    traverse(root->l,str+"0");
+    //if(root->r)
+    traverse(root->r,str+"1");
+}
+int main() {
+	//code
+	
+	int t; //for number of test cases
+	cin>>t;
+	while(t--)
+	{
+	    string s;
+	    cin>>s;
+	    priority_queue<node*,vector<node*>,compare> pq;//minheap;
+	    
+	    
+	    int x;
+	    for(int i=0;i<s.length();i++)
+	    {
+	        struct node *nn=(struct node *)malloc(sizeof(struct node));
+	        cin>>x;
+	        nn->freq=x;
+	        nn->data=s[i];
+	        nn->l=nn->r=NULL;
+	        pq.push(nn);
+	    }
+	    
+	   while(pq.size()!=1)
+	    {
+	        struct node *left=pq.top();
+	        pq.pop();
+	        
+	        struct node *right=pq.top();
+	        pq.pop();
+	        
+            node *heapNode=(node*)malloc(sizeof(node));
+            heapNode->data='#'; //  '#'' acts as character in intermediate nodes 
+            heapNode->freq=left->freq+right->freq;
+            heapNode->l=left;
+            heapNode->r=right;
+            
+            pq.push(heapNode);
+	    }
+	    
+	    struct node *root=pq.top();
+	        string ans="";
+	        traverse(root,ans);
+	        cout<<endl;
+	        
+	}
+	return 0;
+}