hdu（1053）

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题目：http://acm.hdu.edu.cn/showproblem.php?pid=1053
霍夫曼编码的题目，要注意n==1时的特殊情况。
#include<stdio.h>#include<iostream>using namespace std;const int inf = 1000000;typedef struct hufcode{    int weight;    int parent;    int depth;    int lson;    int rson;    void set(){parent = -1;depth= 0;lson = -1;rson= -1;}}hc;hc *node;int hash[30];char str[100];int build(int n){    int maxn = 2*n - 1;    int min1,min2,s1,s2;    for(inti = 0;i <n;i++)       node[i].set();    int j = 0;    for (int i = 0; i < 27; i++)       if(hash[i])          node[j++].weight = hash[i];    s1 = 0;    for(inti = 0;i <n-1;i++){       min1 = min2 = inf;       for(intj = 0;j <i+n;j++){          if(node[j].parent == -1 && min1> node[j].weight){              s2 = s1;              min2 = min1;              min1 = node[j].weight;              s1 = j;           }          else if(node[j].parent == -1 && min2> node[j].weight){              min2 = node[j].weight;              s2 = j;           }       }       node[i+n].weight = node[s1].weight + node[s2].weight;       node[i+n].parent = -1;       node[i+n].lson = s1;       node[i+n].rson = s2;       node[s1].parent = n+i;       node[s2].parent = n+i;    }    return maxn - 1;}void getdepth(int root,int depth){    if(node[root].lson == -1 &&node[root].rson == -1)       node[root].depth = depth;    else if(node[root].lson == -1)       getdepth(node[root].rson, depth+1);    else if(node[root].rson == -1)       getdepth(node[root].lson, depth+1);    else{       getdepth(node[root].lson, depth+1);       getdepth(node[root].rson, depth+1);    }}int main(){    int root,result;   node =(hufcode*)calloc(60,sizeof(hufcode));    while(scanf("%s",str)&&strcmp(str,"END")){       memset(hash, 0, sizeof(hash));       int len =(int)strlen(str);       for(inti = 0 ;i <len;i++)          if(str[i] == '_')              hash[26]++;          else              hash[str[i]-'A']++;       //for(int i = 0;i< 30;i++)        //  printf("%d ",hash[i]);       int n =0;       for(inti = 0;i <27;i++)          if(hash[i])              n++;       if(n==1){          printf("%d %d 8.0\n",len*8,len);          continue;       }       root = build(n);       getdepth(root, 0);       int j =0;       result = 0;       for(int i = 0; i < 27; i++)          if(hash[i]){             //printf("%d %d\n",node[j].depth,hash[i]);              result += node[j++].depth*hash[i];           }       printf("%d %d%.1lf\n",len*8,result,(double)(len*8)/result);    }    free(node);    return 0;}
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