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哈夫曼編碼的實現(讀入檔案的形式)

#include<bits/stdc++.h>
using namespace std;
int w[30];
typedef struct
{
	int weight;
	int parent,lchild,rchild;
}HTNode,*HuffmanTree;

typedef char **HuffmanCode;

void Select(HuffmanTree HT,int n,int &s1,int &s2)
{
	int i,min;
	for (i=1;i<=n;i++)
		if (HT[i].parent==0)
		{
			min = i;
			break;
		}
	for (i=1;i<=n;i++)
		if (HT[i].parent==0)
			if (HT[i].weight<HT[min].weight)
				min = i;
	s1 = min;
	for (i=1;i<=n;i++)
		if (HT[i].parent==0 && i!=s1)
		{
			min = i;
			break;
		}
	for (i=1;i<=n;i++)
		if (HT[i].parent==0 && i!=s1)
			if (HT[i].weight<HT[min].weight)
				min = i;
	s2 = min;
}

void CreateHuffmanTree(HuffmanTree &HT,int n)
{
	int m,i,s1,s2;
	if (n<=1) return;
	m = 2 * n - 1;
	HT = new HTNode[m+1];
	for (i=1;i<=m;i++)
	{
		HT[i].parent = 0;
		HT[i].lchild = 0;
		HT[i].rchild = 0;
	}
	for (i=1;i<=n;i++)
		HT[i].weight = w[i];
	for (i=n+1;i<=m;i++)
	{
		Select(HT,i-1,s1,s2);
		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;
	}
	printf("\n i   weight  parent  lchild  rchild \n");
	for(int i=1; i<=m; ++i)
        printf("%2d %5d %8d %8d %8d\n",i,HT[i].weight,HT[i].parent,HT[i].rchild,HT[i].lchild);

}

void CreatHuffmanCode(HuffmanTree HT,HuffmanCode &HC,int n,int len,char s[])
{
	HC = new char*[n+1];
	char *cd = new char[n];
	int i,start,f,c,w = 0;
	cd[n-1] = '\0';
	for (i=1;i<=n;i++)
	{
		start = n - 1;
		c = i;f = HT[i].parent;
		while (f!=0)
		{
			start--;
			if (HT[f].lchild==c) cd[start] = '0';
			else cd[start] = '1';
			c = f;f = HT[f].parent;
		}
		HC[i] = new char[n-start];
		strcpy(HC[i],&cd[start]);
	}
	delete cd;
	printf(" i  Char   Code\n\n");
    for(int i=1; i<=n; ++i)
        printf("%2d   %c     %s\n",i,i+'A'-1,HC[i]);
    for (int i=0;i<len;i++)
    	printf("%s",HC[s[i]-'A']+1);
}

int main()
{
	freopen("in.txt","r",stdin);
	freopen("out.txt","w",stdout);
	char s[1000];
	scanf("%s",s);
	int len = strlen(s);
	memset(w,0,sizeof(w));
	for (int i=0;i<len;i++)
		w[s[i]-'A'+1]++;
	int n = 0;
	for (int i=1;i<=26;i++)
		if (w[i]) n++;
	for (int i=1;i<=26;i++)
		if (w[i]) printf("%c : %d\n",'A'+i-1,w[i]);
	HuffmanTree HT;
	HuffmanCode HC;
	CreateHuffmanTree(HT,n);
	CreatHuffmanCode(HT,HC,n,len,s);
	return 0;
}