優先キュー解Huffman符号化c++

     priority_queue           ，T     ，Container        ，，Compare       ，  Container           ，  vector,deque，   list.STL          vector.         operator< ,                 ，         。        ，                。STL           greater<Type>，                   。   (DanielWang_).
　　   Huffman    ,           ,          .                 ,            ,          .

 
 
 
typedef struct HTNode{
    char c;
    unsigned int freq;
    HTNode *lchild, *rchild;

    //    
    HTNode(char key='\0', unsigned int fr=0, HTNode *l=NULL, HTNode *r=NULL):
        c(key),freq(fr),lchild(l),rchild(r){};

}HTNode,*pNode;

//             
struct cmp{
    bool operator()(pNode node1, pNode node2){
        return node1->freq > node2->freq;
    }
};

//           
priority_queue<pNode, vector<pNode>, cmp> pq;
  
 
　　2. 具体实现代码 
 
 
   Huffman      ,    string     ,erase,       .  end()  string             ,                   .
str.erase(str.end()-1);        //        
  
 
  
*************************************************************************
    > File Name: Huffman_code_pg.cpp
    > Author: He Xingjie
    > Mail: gxmshxj@163.com
    > Created Time: 2014 06 06      08 57 01 
    > Description: 
 ************************************************************************/
#include<iostream>
#include<queue>
#include<vector>
#include<cstdio>
#include<stack>

using namespace std;

typedef struct HTNode{
    char c;
    unsigned int freq;
    HTNode *lchild, *rchild;

    //    
    HTNode(char key='\0', unsigned int fr=0, HTNode *l=NULL, HTNode *r=NULL):
        c(key),freq(fr),lchild(l),rchild(r){};

}HTNode,*pNode;

//             
struct cmp{
    bool operator()(pNode node1, pNode node2){
        return node1->freq > node2->freq;
    }
};

//           
priority_queue<pNode, vector<pNode>, cmp> pq;

void HuffmanCode(int n)
{
    pNode l, r;

    //                  ,  ， 
    //          
    while (pq.size() > 1)
    {
        pNode z = new HTNode;

        l = pq.top();
        pq.pop();
        r = pq.top();
        pq.pop();

        z->lchild = l;
        z->rchild = r;
        z->freq = l->freq + r->freq;

        pq.push(z);
    }
}

void PrintCode(pNode t, string str)
{
    //      HuffmanTree  HuffmanCode
    if (t == NULL)
        return;
    if (t->lchild)
    {
        str += '0';
        PrintCode(t->lchild, str);
    }

    //    
    if (t->lchild == NULL && t->rchild == NULL)
    {
        cout<<t->c<<"'s code: "<<str<<endl;
    }

    str.erase(str.end()-1);        //        

    if (t->rchild)
    {
        str += '1';
        PrintCode(t->rchild, str);
    }
}

void DFS(HTNode *t)
{
    HTNode *node;
    stack<pNode, vector<pNode> > pstack;

    pstack.push(t);
    node = pstack.top();
    pstack.pop();

    while (pstack.size() > 0)
    {
        if (node->lchild)
        {
            pstack.push(node->lchild);
            node = node->lchild;     
        }
        else if(node->rchild)
        {
            pstack.push(node->rchild);
            node = node->rchild;
        }
        else
        {
            printf("%d ", node->freq);
            node = pstack.top();
            pstack.pop();
        }
    }
}

int main()
{
    int n, i;
    FILE *fp;
    char tmp;
    string str;

    fp = fopen("in.txt", "r");
    if (fp ==NULL)
    {
        printf("fopen error!
");
        return -1;
    }

    //    
    fscanf(fp, "%d", &n);
    fscanf(fp, "%c", &tmp);

    //    
    for (i=0; i<n; i++)
    {
        char c;
        int freq;
        pNode p = new HTNode;

        fscanf(fp, "%c%d", &c, &freq);
        p->c = c;
        p->freq = freq;
        
        fscanf(fp, "%c", &tmp);

        pq.push(p);
    }

    HuffmanCode(n);
    PrintCode(pq.top(), str);

    return 0;
}
  
参照先:
http://www.cplusplus.com/reference/queue/priority_queue/?kw=priority_queue  
http://blog.csdn.net/liuzhanchen1987/article/details/7856893  
http://blog.csdn.net/daniel_ustc/article/details/17613359