哈夫曼树的生成以及编码

哈夫曼树的生成以及编码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include<iostream>
using namespace std;

typedef int ELEMTYPE;
typedef struct HuffmanTree
{
	ELEMTYPE weight;
	char value;
	struct HuffmanTree* lchild;
	struct HuffmanTree* rchild;
}HuffmanNode;

// 构建哈夫曼树
HuffmanNode* createHuffmanTree(int* a,char* b,int n)
{
	int i, j;
	HuffmanNode **temp, *hufmTree;
	temp = (HuffmanNode **)malloc(n * sizeof(HuffmanNode));
	for (i = 0; i < n; ++i)     // 将数组a中的权值赋给结点中的weight
	{
		temp[i] = (HuffmanNode*)malloc(sizeof(HuffmanNode));
		temp[i]->weight = a[i];
		temp[i]->lchild = temp[i]->rchild = NULL;
		temp[i]->value = b[i];
	}

	for (i = 0; i < n - 1; ++i)       // n-1次合并
	{
		int small1 = -1, small2;      // small1、small2分别作为最小和次小权值的下标
		for (j = 0; j < n; ++j)         // 先将最小的两个下标赋给small1、small2（注意：对应权值未必最小）
		{
			if (temp[j] != NULL && small1 == -1)
			{
				small1 = j;
				continue;
			}
			else if (temp[j] != NULL)
			{
				small2 = j;
				break;
			}
		}
		if (small1 > small2)
		{
			int t = small1;
			small1 = small2;
			small2 = t;
		}
		for (j = small2; j < n; ++j)    // 比较权值，挪动small1和small2使之分别成为最小和次小权值的下标
		{
			if (temp[j] != NULL)
			{
				if (temp[j]->weight < temp[small1]->weight)
				{
					small2 = small1;
					small1 = j;
				}
				else if (temp[j]->weight < temp[small2]->weight)
				{
					small2 = j;
				}
			}
		}
		hufmTree = (HuffmanNode*)malloc(sizeof(HuffmanNode));
		hufmTree->weight = temp[small1]->weight + temp[small2]->weight;
		hufmTree->lchild = temp[small1];
		hufmTree->rchild = temp[small2];

		temp[small1] = hufmTree;
		temp[small2] = NULL;
	}
	return hufmTree;
}


// 递归进行哈夫曼编码
void HuffmanCode(HuffmanNode* hufmTree, int depth,int*code)      // depth是哈夫曼树的深度
{
	if (hufmTree)
	{
		if (hufmTree->lchild == NULL && hufmTree->rchild == NULL)
		{
			printf("%c的哈夫曼编码为 ",  hufmTree->value);
			int i;
			for (i = 0; i < depth; ++i)
			{
				printf("%d", code[i]);
			}
			printf("\n");
		}
		else
		{
			code[depth] = 0;
			HuffmanCode(hufmTree->lchild, depth + 1,code);
			code[depth] = 1;
			HuffmanCode(hufmTree->rchild, depth + 1,code);
		}
	}
}



int main()
{
	int i, n;
	char string[100];
	printf("请输入叶子结点的个数：\n");
	

	scanf("%d", &n);
	
	int* arr;
	arr = (int*)malloc(n * sizeof(ELEMTYPE));
	printf("请输入%d个叶子结点的权值及其各自代表的字符：\n", n);
	for (i = 0; i < n; ++i)
	{
		printf("第%d个",i+1); 
		scanf("%d", &arr[i]);
		scanf("%c", &string[i]);
	}
	HuffmanNode* hufmTree = NULL;
	hufmTree = createHuffmanTree(arr,string,n);
	int code[100];
	printf("\n各叶子结点的哈夫曼编码为：\n");
	HuffmanCode(hufmTree, 0,code);

	return 0;
}

注意输入时权值与字符之间不加符号，否则会将空格当作字符，可以加一个getchar（）来实现。

本文改编自
https://blog.youkuaiyun.com/F__shigang/article/details/65442550
删改了一些内容。