哈夫曼树

最新推荐文章于 2021-12-10 00:45:02 发布

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本文详细介绍了一种基于哈夫曼树的编码实现方法，包括结构定义、创建哈夫曼树的过程以及编码路径的生成。通过示例展示了如何使用优先队列进行节点合并，最终得到最优的编码方案。

.h文件

#pragma once
#include <iostream>
#include <vector>
#define MAX 1000
//哈夫曼结构
struct HuffmanTree {
	float data;
	char c;
	HuffmanTree* left;
	HuffmanTree* right;
	int flag;   //左0右1
	HuffmanTree(float x,char cc) {
		data = x;
		c = cc;
		left = right = NULL;
	}
	HuffmanTree(float x, HuffmanTree* l, HuffmanTree* r) {
		data = x;
		left = l;
		right = r;
	}
};

struct goLeft {
	char c;
	std::vector<int> v;
};

.cpp文件

#include "pch.h"
#include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
#include <string>
#include "HuffmanTree.h"
#include "printTree.h"
using namespace std;
//适配器
struct cmp {

	bool operator()(HuffmanTree* &s1, HuffmanTree* &s2) {
		return s1->data > s2->data;	//升序
	}
};
bool compare( goLeft& v1, goLeft& v2) {
	return v1.c < v2.c;
}

//创建哈夫曼树
HuffmanTree* createHuffman(float[], char c[],int n,
	priority_queue<HuffmanTree*, vector<HuffmanTree*>, cmp>& Q) {
	//n个节点  n-1次合并 到最后只有一个根
	for (int i = 0; i < n-1; i++) {
		//找出两个最小节点
		HuffmanTree* h1 = Q.top();
		h1->flag = 0;
		Q.pop();
		HuffmanTree* h2 = Q.top();
		h2->flag = 1;
		Q.pop();
		//合并两个最小节点的值 构造新节点  新节点左小右大链接两个小节点
		HuffmanTree* h = new HuffmanTree(h1->data + h2->data,h1,h2);
		//重新入堆
		Q.push(h);
	}
	//队列中只有一个节点  哈夫曼树最终的根
	return Q.top();
}


vector<int> v;
vector<goLeft> go;
//按序打印叶子节点的编码
void pringGoLeft() {
	sort(go.begin(), go.end(), compare);
	for (int i = 0; i < go.size(); i++) {
		cout << go[i].c << ": ";
		for (int j = 0; j < go[i].v.size(); j++)
			cout << go[i].v[j];
		cout << endl;
	}
	
}
void createPath(HuffmanTree* node) {
	if (node->left == NULL && node->right == NULL) {
		//不是按序输出
		//cout << node->c << ": ";
		//for (int i = 0; i < v.size(); i++)
		//	cout << v[i];
		//cout << endl;
		goLeft g;
		g.c = node->c;
		for (int i = 0; i < v.size(); i++)
			g.v.push_back(v[i]);
		go.push_back(g);
		return;
	}
	v.push_back(node->left->flag);
	createPath(node->left);
	v.pop_back();
	v.push_back(node->right->flag);
	createPath(node->right);
	v.pop_back();
}
int main()
{
	priority_queue<HuffmanTree*, vector<HuffmanTree*>, cmp> Q;	//哈夫曼队列
	float f[] = { 45,13,12,16,9,5 };	//字符的频率
	char c[] = { 'a','b','c','d','e','f' };	//字符
	int n = sizeof(f) / sizeof(float);
	for (int i = 0; i < n; i++)	
		Q.push(new HuffmanTree(f[i],c[i]));


	HuffmanTree* root = createHuffman(f,c,n,Q);

	createPath(root);
	pringGoLeft();
	

	return 0;
}