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huffmanDecoding.cpp
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huffmanDecoding.cpp
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#include<bits/stdc++.h>
using namespace std;
map<char, int > FF; // frequency
map<char,string > encr;
struct node{
int freq;
char data;
node *left,*right;
node(){
}
node(char dta, int fq){
data = dta;
freq = fq;
left = nullptr;
right = nullptr;
}
~node(){
delete left;
delete right;
}
};
node *Root = nullptr;
struct cmp{
bool operator()(node* l, node* r){
return (l->freq > r->freq);
}
};
class huffman{
public:
void Encode(string s){
priority_queue<node*, vector<node*> , cmp > minHeap;
for(int i = 0; i < (int)s.length(); i++){
minHeap.push(new node(s[i], FF[s[i]]) );
}
while(minHeap.size() != 1){
node *l = minHeap.top();
minHeap.pop();
node *r = minHeap.top();
minHeap.pop();
node *N = new node('$' , l->freq + r->freq);
N->left = l;
N->right = r;
minHeap.push(N);
}
Root = minHeap.top();
printCode(minHeap.top(), "");
}
void printCode(node *root, string str){
if(root == nullptr){
return;
}
if(root->data != '$'){
cout<<root->data<<" : "<<str<<endl;
encr[root->data] = str;
}
printCode(root->left,str + "0");
printCode(root->right, str + "1");
}
string decode(node *root, string coded ){
node *curr = root;
string ans = "";
for(int i = 0; i < (int)coded.size(); i++){
if(coded[i] == '0'){
curr = curr->left;
}
else{
curr = curr->right;
}
if(curr->left == nullptr and curr->right == nullptr){
ans += curr->data;
curr = root;
}
}
return ans;
}
};
int main(){
int T;
cin>>T;
while(T--){
string s;
cin>>s;
for(int i = 0; i < (int)s.length(); i++){
FF[s[i]]++;
}
string str ;
for(auto it = FF.begin(); it!=FF.end(); ++it){
str += it->first;
}
huffman ob;
ob.Encode(str);
string coded= "";
for(int i = 0 ; i< (int)s.length(); i++){
cout<<encr[s[i]];
coded += encr[s[i]];
}
cout<<endl;
cout<<ob.decode(Root,coded);
cout<<endl;
}
}