电文译码

电文译码

根据一棵哈夫曼树，将电文码翻译为对应的权重
首先建立一棵哈夫曼树

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define N 4
typedef struct HTnode{
	int weight;
	int parent,lchild,rchild;
}HTnode,*HFtree;
typedef char** HFcode;
void selectnode(HFtree HT,int n,int &s1,int &s2)//选择没有双亲，权重最小的两个 
{
	int i;
	for(i=1;i<=n;i++)
	{
		if(HT[i].parent==0)
		s1=i;
	}
	for(i=1;i<=n;i++)
	{
		if(HT[i].parent==0)
		{
			if(HT[i].weight<HT[s1].weight)
			s1=i;
		}
	}
	
	for(i=1;i<=n;i++)
	{
		if(HT[i].parent==0&&i!=s1)
		s2=i;
	}
	for(i=1;i<=n;i++)
	{
		if(HT[i].parent==0)
		{
			if(HT[i].weight<HT[s2].weight&&i!=s1)
			s2=i;
		}
	}		
}
void initHFtree(HFtree &HT,int n,int *w)//建立哈夫曼树 
{
	int m=2*n-1;
	HT=(HFtree)malloc((m+1)*sizeof(HTnode));
	int i;
	HT[0].weight=m;
	
	for(i=1;i<=n;i++)
	{
	HT[i].parent=HT[i].lchild=HT[i].rchild=0;
	HT[i].weight=w[i-1];		
	}
	for(i=n+1;i<=m;i++)
	HT[i].weight=HT[i].lchild=HT[i].rchild=HT[i].parent=0;
	for(i=n+1;i<=m;i++)
	{
		int s1,s2;
		selectnode(HT,i-1,s1,s2);
		HT[i].weight=HT[s1].weight+HT[s2].weight;
		HT[i].lchild=s1;
		HT[i].rchild=s2;
		HT[s2].parent=HT[s1].parent=i;
	}
}

进行翻译

void translate(HFtree HT,int n,char *s)
{
	int c=2*n-1;
	for(int i=0;i<strlen(s);i++)
	{
		if(HT[c].lchild&&HT[c].rchild)
		{
			if(s[i]=='1') c=HT[c].rchild;
			else c=HT[c].lchild;
			if(HT[c].lchild==0&&HT[c].rchild==0)
			{
				printf("%d",HT[c].weight);
				c=2*n-1;
			}
		}
	}
}

5的哈希码是10
7的哈希码是0
2的哈希码是110
4的哈希码是111

int main()
{
	int w[100]={7,5,2,4};
	char s[100]="101110110111"; 
	HFtree HT;
	initHFtree(HT,N,w);
	for(int j=1;j<=2*N-1;j++)
	printf("%d:  %2d %2d %2d %2d\n",j,HT[j].weight,HT[j].parent,HT[j].lchild,HT[j].rchild);
	translate(HT,N,s);
	
 }