hdu1053:Entropy 之霍夫曼编码

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

用优先队列做，不过要注意不能用指针!

一开始用指针*lchild,*rchild，结果悲剧了!,好像说类或结构体中有指针,对象赋值时会存在危险,所以果断不用指针！

如有大神用指针AC该题，求代码!!!!

#include<iostream>
#include<cmath>
#include<cstdio>
#include<queue>
#include<iomanip>
using namespace std;

const int maxn = 1000000;
char str[maxn];
bool flag[27];
int bitnum;
int t;
int yx[27];
struct node{
    double frequency;
    bool isleaf;
    int bitn;
    int index;
    int length;
    int lchild, rchild;
    friend bool operator <(const node &n1, const node &n2){
        return n1.frequency > n2.frequency;
    }
}nd[60];

void computeBit(node root, int len){

    if (root.isleaf){
        bitnum += len*root.bitn;
    }
    else{
        
            computeBit(nd[root.lchild], len + 1);
            computeBit(nd[root.rchild], len + 1);
    }

}
void createHuffmTree(int origbitn){
    priority_queue<node> q;
    int i;
    for (i = 0; i < t; i++){
        q.push(nd[i]);
    }
    while (q.size() >= 2){
        node nl = q.top();
        q.pop();
        node nr = q.top();
        q.pop();
        node merge;
        merge.frequency = nl.frequency + nr.frequency;
        merge.isleaf = false;
        merge.lchild = nl.index;
        merge.rchild = nr.index;
        merge.index = t;
        nd[t] = merge;
        t++;
        q.push(merge);
    }
    bitnum = 0;
    if (q.size() == 1){
        if (q.top().lchild == -1){
            bitnum = q.top().bitn * 1;
        }
        else{
            computeBit(q.top(), 0);
        }
    }
    double fracy = double(origbitn) / double(bitnum);
    cout << bitnum << " " << setiosflags(ios::fixed)<<setprecision(1)<< fracy << endl;

}
int input(){
    char c;
    int cnt = 0;
    t = 0;
    int i;
    int g;
    int nm = 0;
    memset(flag, false, sizeof(flag));
    while ((c = getchar()) != '\n'){
        str[cnt++] = c;
        if (c == '_'){
            g = 26;
        }
        else
            g = c - 'A';
        if (!flag[g]){

            flag[g] = true;
            yx[g] = t;
            nd[t].bitn = 1;
            nd[t].index = t;
            nd[t].isleaf = true;
            nd[t].lchild = nd[t].rchild = -1;
            t++;
            nm++;
        }
        else{
            int b = yx[g];
            nd[b].bitn++;
        }
    }


    str[cnt] = '\0';
    if (strcmp(str, "END") == 0){
        return 0;
    }
    cout << (cnt * 8) << " ";
    for (i = 0; i < t; i++){
        nd[i].frequency = double(nd[i].bitn) / double(cnt);
    }
    createHuffmTree(cnt * 8);
    return 1;
}
int main(){
    while (true){
        if (!input()){
            break;
        }
    }
    return 0;
}