//优先级队列实现的哈夫曼树的编码和译码   

#include<iostream>
#include<queue>
#include<string>
using namespace std;    class Node
{
public:    float weight;    Node* left;    Node* right;    char ch;    Node(float w,Node* l=NULL,Node* r=NULL,char c=' '):weight(w),ch(c),left(l),right(r) {}    Node(float w,char c=' '):weight(w),ch(c),left(NULL),right(NULL) {}
};    class cmp
{
public :    bool operator()(Node* a,Node* b)    {    return a->weight>b->weight;    }
};  vector<int> v;
void Encode(Node* r)//打印字符的编码
{     if(r->left==NULL && r->right==NULL)     {     cout << r->ch <<": ";     for (int i = 0;i<v.size();++i)     cout << v[i];     cout << endl;     v.pop_back();     return ;     }     if(r->left)     {     v.push_back(0);     Encode(r->left);     }     if(r->right)     {     v.push_back(1);     Encode(r->right);     }    if(!v.empty())    {    v.pop_back();    }
}    void Decode(Node* root, string s)//译码
{    Node* p=root;    for(int i=0;i<s.length();++i)    {    if(s[i]=='0')     {    if(p->left) p=p->left;    else     {    cout<<s<<" Can't decode!"<<endl;    return ;    }    }     if(s[i]=='1')     {     if(p->right) p=p->right;    else     {    cout<<s<<" Can't decode!"<<endl;     return ;    }    }    }    cout<<s<<": "<<p->ch<<endl;
}    void freeTree(Node* p)//销毁哈夫曼树
{    if(p->left!=NULL)    freeTree(p->left);    if(p->right!=NULL)    freeTree(p->right);    delete p;    p=NULL;
}    int main()
{    Node* m1,*m2;    char ch[]={'A','C','E','D','F','G'};//字符       float f[]={0.1,0.3,0.4,0.5,0.2,0.6};//频率
  priority_queue<Node*,vector<Node*>,cmp> q;    int n=sizeof(ch)/sizeof(ch[0]);    for(int i=0;i<n;++i)    {    q.push(new Node(f[i],ch[i]));    cout<<ch[i]<<": "<<f[i]<<'\t';     }    cout<<endl;    for(int i=1;i<n;++i)    {    m1=q.top(); q.pop();    m2=q.top(); q.pop();    float w=m1->weight+m2->weight;    q.push(new Node(w,m1,m2));    }    Node* root=q.top();    Encode(root);    cout<<endl;    Decode(root,"1011");    freeTree(root);    return 0;
}