哈夫曼编码C++实现

#include <stdio.h>#include <limits.h>#include <string.h>#include <stdlib.h>#define N 6typedef struct huffNode{    unsigned int weight;   //权重    unsigned int lchild,rchild,parent;  //左右子节点和父节点}HTNode,*HuffTree;typedef char **HuffCode;//找出数组中无父节点且权值最小的两个节点下标,分别用s1和s2保存void select(const HuffTree &HT,int n,int &s1,int &s2);//HT:哈夫曼树，HC:哈夫曼编码，w:构造哈夫曼树节点的权值，n:构造哈夫曼树节点的个数void HuffmanCode(HuffTree &HT,HuffCode &HC,int *w,int n);int main(){    int i;    char key[N] = {'0','A','B','C','D','E'};//第0个元素保留不用    int w[N] = {0,1,2,4,5,6}; //第0个元素保留不用    HuffTree HT;    HuffCode HC;    HuffmanCode(HT,HC,w,N - 1);    for ( i = 1; i < N; i++ )    printf("%c:%s\n",key[i],HC[i]);    printf("\n");    return 0;}//找出数组中权值最小的两个节点下标,分别用s1和s2保存void select(const HuffTree &HT,int n,int &s1,int &s2){    int i;    s1 = s2 = 0;    int min1 = INT_MAX;//最小值，INT_MAX在<limits.h>中定义的    int min2 = INT_MAX;//次小值    for ( i = 1; i <= n; ++i )    {    if ( HT[i].parent == 0 )    {//筛选没有父节点的最小和次小权值下标        if ( HT[i].weight < min1 )        {//如果比最小值小        min2 = min1;        s2 = s1;        min1 = HT[i].weight;        s1 = i;        }        else if ( (HT[i].weight >= min1) && (HT[i].weight < min2) )        {//如果大于等于最小值，且小于次小值        min2 = HT[i].weight;        s2 = i;        }        else        {//如果大于次小值，则什么都不做        ;        }    }    }}//HT:哈夫曼树，HC:哈夫曼编码，w:构造哈夫曼树节点的权值，n:构造哈夫曼树节点的个数void HuffmanCode(HuffTree &HT,HuffCode &HC,int *w,int n){    int s1;    int s2;    int m = 2 * n - 1;       //容易知道n个节点构造的哈夫曼树是2n-1个节点    int i,c,f,j;    char *code;  //暂存编码的    HT = (HuffTree)malloc((m+1)*sizeof(HTNode));  //0单元未使用    for ( i = 1; i <= n; i++ )        HT[i] = {w[i],0,0,0};//初始化前n个节点(构造哈夫曼树的原始节点)    for ( i = n + 1; i <= m; i++ )    HT[i] = {0,0,0,0};  //初始化后n-1个节点    //构建哈夫曼树    for ( i = n + 1; i <= m; i++)    {    select(HT,i-1,s1,s2);//找出前i-1个节点中权值最小的节点下标    HT[s1].parent = i;    HT[s2].parent = i;    HT[i].lchild = s1;    HT[i].rchild = s2;    HT[i].weight = HT[s1].weight + HT[s2].weight;    }    //哈夫曼编码    HC = (char **)malloc((n)*sizeof(char *));    //暂存编码    code = (char *)malloc(n*sizeof(char));//使用了第0单元    code[n-1] = '\0';    for ( i = 1; i <= n; i++ )    {        int start = n-1;    for ( c = i, f = HT[c].parent; f != 0; c = HT[c].parent, f = HT[c].parent )    {//从叶子扫描到根        if ( HT[f].lchild == c )        {        code[--start] = '0';        }        else if(HT[f].rchild == c)        {        code[--start] = '1';        }        else        {//否则什么也不做        ;        }    }    HC[i] = (char *)malloc(strlen(code)*sizeof(char));    strcpy(HC[i],&code[start]);    }}