Entropy （huffman) 优先队列）

http://acm.hdu.edu.cn/showproblem.php?pid=1053

Huffman问题利用STL中的priority_queue解决；

 #include<stdio.h>
 #include<iostream>
 #include<string>
 #include<algorithm>
 #include<map>
 #include<queue>
 using namespace std;

 struct cmp
 {
     bool operator()(const int a, const int b)
     {
         return a > b;
     }
 };
 int solve(string str)
 {
     priority_queue< int,vector<int>,cmp >que;
     map<char, int> mymap;
     int i;
     for(i =; i < str.size(); i++)
     {
         mymap[str[i]]++;
     }

     map<char,int>::iterator it = mymap.begin();
     while(it != mymap.end())
     {
         //printf("%c %d\n",it->first,it->second);
         que.push(it->second);
         it++;
     }

     int weight = ;
     if(que.size() == )
         return que.top();

     while(que.size() != )
     {
         int a,b;
         a = que.top();
         que.pop();
         b = que.top();
         que.pop();

         weight += a+b;
         que.push(a+b);
     }
     return weight;
 }
 int main()
 {
     int weight;
     string str;
     while(cin>>str)
     {
         if(str == "END")
             break;
         weight = solve(str);
         printf("%d %d %.1lf\n",*str.size(),weight,8.0*str.size()/weight);
     }
     return ;
 }