[数据结构][C语言]———哈夫曼编码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
typedef struct{
	int weight;
	int parent,lchild,rchild;
}HTNode,*HuffmanTree;

void Select(HuffmanTree* HT,int n,int* s1,int* s2){
	*s1=*s2=0;
	(*HT)[0].weight=999; 
	for(int i=1;i<=n;i++){
		if((*HT)[i].parent==0){
			if((*HT)[i].weight<(*HT)[*s1].weight)
			{
				*s2=*s1;
				*s1=i;	
			}
			else if((*HT)[i].weight<(*HT)[*s2].weight)
				*s2=i;
		}
	}
}
void HuffmanCoding(HuffmanTree* HT,char*** HC,int n){
	if(n<=1)
		return;
	int m=2*n-1,s1,s2;
	//初始化
	(*HT)=(HuffmanTree)malloc(sizeof(HTNode)*(m+1));
	for(int i=1;i<=m;i++){
		(*HT)[i].parent=0;
		(*HT)[i].lchild=0;
		(*HT)[i].rchild=0;
	}
	 for(int i=1;i<=n;i++){
	 	printf("请输入第%d个字符对应的权值:",i); 
	 	scanf("%d",&((*HT)[i].weight));
	}
	//构建剩下的n-1个结点
	for(int i=n+1;i<=m;i++){
		Select(HT,i-1,&s1,&s2);
		(*HT)[i].weight=(*HT)[s1].weight+(*HT)[s2].weight;
		(*HT)[i].lchild=s1;
		(*HT)[i].rchild=s2;
		(*HT)[s1].parent=(*HT)[s2].parent=i;	
	} 
	//求哈夫曼树
	(*HC)=(char**)malloc(sizeof(char*)*(n+1));
	char* cd= (char*)malloc(sizeof(char)*n);
	cd[n-1]='\0';
	for(int i=1;i<=n;i++){
		int flag=n-1;
		int c=i;
		int parent=(*HT)[i].parent;
		while(parent!=0){
			flag--;
			if((*HT)[parent].lchild==c)
				cd[flag]='0';
			else
				cd[flag]='1';
			c=parent;
			parent=(*HT)[parent].parent;
		}
		(*HC)[i]=(char*)malloc((n-flag)*sizeof(char));
		strcpy((*HC)[i], &cd[flag]);
	}
	free(cd); 
}


int main() {
	HuffmanTree HT;
	char** HC;
	printf("请输入待编码字符个数:");
	int n;
	scanf("%d", &n);
	HuffmanCoding(&HT, &HC, n);
	for (int i = 1;i <= 2 * n - 1;i++) {
		printf("%d:\t%d\t%d\t%d\t%d\n", i, HT[i].weight, HT[i].parent, HT[i].lchild, HT[i].rchild);
	}
	for (int i = 1;i <= n;i++) {
		printf("权值为%d的哈夫曼编码:%s\n", HT[i].weight,HC[i]);
	}
}