Huffman Coding

#include<iostream>
#include <bits/stdc++.h> 
using namespace std; 

struct MinHeapNode 
{ 
    char number; 
    unsigned freq; 
    MinHeapNode *left, *right; 
    MinHeapNode(char number, unsigned freq) 
    { 
        left = right = NULL; 
        this->number = number; 
        this->freq = freq; 
    } 
}; 
struct compare {
    bool operator()(MinHeapNode* l, MinHeapNode* r) 
    { 
        return (l->freq > r->freq); 
    } 
}; 
void printCodes(struct MinHeapNode* root, string code) 
{ 
  
    if (!root) 
        return; 
  
    if (root->number != '$') 
        cout << root->number<< ": "<<code<<"\n"; 
  
    printCodes(root->left,code+"0"); 
    printCodes(root->right,code+"1"); 
} 
void Huffman(char number[], int freq[], int size) 
{ 
    struct MinHeapNode *left, *right, *top; 
    priority_queue<MinHeapNode*, vector<MinHeapNode*>, compare> minHeap; 
  
    for (int i = 0; i < size; ++i) 
        minHeap.push(new MinHeapNode(number[i], freq[i])); 
    while (minHeap.size() != 1) 
    { 
        left = minHeap.top(); 
        minHeap.pop(); 
  
        right = minHeap.top(); 
        minHeap.pop(); 
        top = new MinHeapNode('$', left->freq + right->freq); 
  
        top->left = left; 
        top->right = right; 
  
        minHeap.push(top); 
    } 
    printCodes(minHeap.top(), ""); 
} 
  
int main() 
{ 
  
    char img[] = {'0','1','2','3','4','5','6','7'}; 
    int freq[] = {1,4,2,3,2,12,10,2}; 
  
    int size = sizeof(img) / sizeof(img[0]); 
  
    Huffman(img, freq, size); 
  
    return 0; 
}