Algorithms/Huffman Coding at main · lmalshan96/Algorithms · GitHub

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class Solution{
public:
    struct Node {
           int data;
           struct Node* left;
           struct Node* right;


       Node(int val)
       {
           data = val;
           left = NULL;
           right = NULL;
       }
   };

   struct cmp {

       bool operator()(Node* l, Node* r)

       {
       return (l->data > r->data);
       }
   };

    void preOrder(Node *root,string s,vector<string>&ans){
        if(!root){
            return;
        }

        if(!root->left && !root->right){
            ans.push_back(s);
        }

        preOrder(root->left,s+"0",ans);
        preOrder(root->right,s+"1",ans);
    }

 vector<string> huffmanCodes(string S,vector<int> f,int n)
 {
     priority_queue<Node*,vector<Node*>,cmp> mh;

     for(int i=0; i<n; i++){
         Node *temp = new Node(f[i]);
               mh.push(temp);
     }

     while(mh.size() != 1){
         Node *left = mh.top();
         mh.pop();
         Node *right = mh.top();
         mh.pop();
         Node *parent = new Node(left->data + right->data);
         parent->left = left;
         parent->right = right;
         mh.push(parent);
     }

     Node *root = mh.top();
     mh.pop();
     vector<string> ans;
     preOrder(root,"",ans);
     return ans;

 }
};