霍夫曼算法

// HuffMan.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAXBIT      100
#define MAXVALUE  10000
#define MAXLEAF     30
#define MAXNODE    MAXLEAF*2 -1

typedef struct
{
int bit[MAXBIT];
int start;
} HCodeType;        /* 编码结构体 */
typedef struct
{
int weight;
int parent;
int lchild;
int rchild;
int value;
} HNodeType;        /* 结点结构体 */



/* 构造一颗哈夫曼树 */
void HuffmanTree(HNodeType HuffNode[MAXNODE], int n)
{
/* i、j： 循环变量，m1、m2：构造哈夫曼树不同过程中两个最小权值结点的权值，
x1、x2：构造哈夫曼树不同过程中两个最小权值结点在数组中的序号。*/
int i, j, m1, m2, x1, x2;
/* 初始化存放哈夫曼树数组 HuffNode[] 中的结点 */
for (i = 0; i<2 * n - 1; i++)
{
HuffNode[i].weight = 0;//权值 
HuffNode[i].parent = -1;
HuffNode[i].lchild = -1;
HuffNode[i].rchild = -1;
HuffNode[i].value = i; //实际值，可根据情况替换为字母  
} /* end for */


 /* 输入 n 个叶子结点的权值 */
for (i = 0; i<n; i++)
{
printf("Please input weight of leaf node %d: \n", i);
scanf_s("%d", &HuffNode[i].weight);
} /* end for */


 /* 循环构造 Huffman 树 */
for (i = 0; i<n - 1; i++)
{
m1 = m2 = MAXVALUE;     /* m1、m2中存放两个无父结点且结点权值最小的两个结点 */
x1 = x2 = 0;
/* 找出所有结点中权值最小、无父结点的两个结点，并合并之为一颗二叉树 */
for (j = 0; j<n + i; j++)
{
if (HuffNode[j].weight < m1 && HuffNode[j].parent == -1)
{
m2 = m1;
x2 = x1;
m1 = HuffNode[j].weight;
x1 = j;
}
else if (HuffNode[j].weight < m2 && HuffNode[j].parent == -1)
{
m2 = HuffNode[j].weight;
x2 = j;
}
} /* end for */
 /* 设置找到的两个子结点 x1、x2 的父结点信息 */
HuffNode[x1].parent = n + i;
HuffNode[x2].parent = n + i;
HuffNode[n + i].weight = HuffNode[x1].weight + HuffNode[x2].weight;
HuffNode[n + i].lchild = x1;
HuffNode[n + i].rchild = x2;


printf("x1.weight and x2.weight in round %d: %d, %d\n", i + 1, HuffNode[x1].weight, HuffNode[x2].weight);  /* 用于测试 */
printf("\n");
} /* end for */
 /*  for(i=0;i<n+2;i++)
 {
 printf(" Parents:%d,lchild:%d,rchild:%d,value:%d,weight:%d\n",HuffNode[i].parent,HuffNode[i].lchild,HuffNode[i].rchild,HuffNode[i].value,HuffNode[i].weight);
 }*///测试 
} /* end HuffmanTree */




  //解码 
void decodeing(char string[], HNodeType Buf[], int Num)
{
int i, tmp = 0, code[1024];
int m = 2 * Num - 1;
char *nump;
char num[1024];
for (i = 0; i<strlen(string); i++)
{
if (string[i] == '0')
num[i] = 0;
else
num[i] = 1;
}
i = 0;
nump = &num[0];


while (nump<(&num[strlen(string)]))
{
tmp = m - 1;
while ((Buf[tmp].lchild != -1) && (Buf[tmp].rchild != -1))
{
if (*nump == 0)
{
tmp = Buf[tmp].lchild;
}
else tmp = Buf[tmp].rchild;
nump++;
}
printf("%d", Buf[tmp].value);
}
}


int main() {
HNodeType HuffNode[MAXNODE];            /* 定义一个结点结构体数组 */
HCodeType HuffCode[MAXLEAF], cd;       /* 定义一个编码结构体数组， 同时定义一个临时变量来存放求解编码时的信息 */
int i, j, c, p, n;
char pp[100];
printf("Please input n:\n");
scanf_s("%d", &n);
HuffmanTree(HuffNode, n);




for (i = 0; i < n; i++)
{
cd.start = n - 1;
c = i;
p = HuffNode[c].parent;
while (p != -1)   /* 父结点存在 */
{
if (HuffNode[p].lchild == c)
cd.bit[cd.start] = 0;
else
cd.bit[cd.start] = 1;
cd.start--;        /* 求编码的低一位 */
c = p;
p = HuffNode[c].parent;    /* 设置下一循环条件 */
} /* end while */


 /* 保存求出的每个叶结点的哈夫曼编码和编码的起始位 */
for (j = cd.start + 1; j<n; j++)
{
HuffCode[i].bit[j] = cd.bit[j];
}
HuffCode[i].start = cd.start;
} /* end for */


 /* 输出已保存好的所有存在编码的哈夫曼编码 */
for (i = 0; i<n; i++)
{
printf("%d 's Huffman code is: ", i);
for (j = HuffCode[i].start + 1; j < n; j++)
{
printf("%d", HuffCode[i].bit[j]);
}
printf(" start:%d", HuffCode[i].start);


printf("\n");


}
/*    for(i=0;i<n;i++){
for(j=0;j<n;j++)
{
printf ("%d", HuffCode[i].bit[j]);
}
printf("\n");
}*/
printf("Decoding?Please Enter code:\n");
scanf_s("%s", &pp);
decodeing(pp, HuffNode, n);
getchar();
return 0;
}