noj 1491 Huffman Coding

 哈夫曼编码

#include<iostream>
#include<queue>
#include<vector>
using namespace std;
const int Max = 2001;

struct Tode {
    int id; 
    int weight;
};

struct node{
    int left , right ;
    int weight;
}p[Max];
int tail,root,ans;

struct cmp{ 
    bool operator() ( Tode a, Tode b ){ 
        return a.weight>b.weight;
    } 
};

priority_queue<Tode,vector<Tode>, cmp > pq;

void creatree(int n){
    for(;;){
        if(pq.size()==1) {
            root = pq.top().id;
            break;
        }
        Tode A = pq.top();  pq.pop();
        Tode B = pq.top();  pq.pop();
        Tode C ; C.id = tail++; C.weight= A.weight +B.weight;
        pq.push(C);
        p[C.id].left = A.id; 
        p[C.id].right = B.id;

    }
}

void dfs(int u,int dept){
    if(p[u].weight!=-1){
        ans+= p[u].weight*dept;
    }
    if(p[u].left!=-1){
        dfs(p[u].left,dept+1);
    }
    if(p[u].right!=-1){
        dfs(p[u].right,dept+1);
    }
}

int main(){
    int n,i;
    for(;cin>>n;){

        tail = n; ans = 0 ;
        for(i=0;i<2*n;i++) {
            p[i].left = -1;
            p[i].right = -1;
            p[i].weight = -1;
        }

        for(;!pq.empty();) pq.pop();

        for(i=0;i<n;i++){
            Tode B;
            cin>>B.weight;
            B.id = i;
            p[i].weight = B.weight;
            pq.push(B);
        }
        if(n==1|| n==0) {
            printf("%d\n",n*pq.top().weight);
            continue;
        }
        
        creatree(n);
        dfs(root,0);

        printf("%d\n",ans);
    }
    return 0;
}