课程设计：C++实现哈夫曼编码

功能实现：

//1:先计算每个字符的权重
//2：构建哈夫曼树
//3：得出每个字符的哈夫曼编码。
//4:根据哈夫曼编码转化为字符

代码实现：

// 哈夫曼编码.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//1:先计算每个字符的权重
//2：构建哈夫曼树
//3：得出每个字符的哈夫曼编码。#include<iostream>
#include<string>
using namespace std;class node {
public:char value;int weight;//权重node* left;node* right;string code;//编码int zhi;node() {left = NULL;right = NULL;zhi = 0;weight = 0;}node( int a) {this->weight = a;}void showa() {cout << value<<"  "<< weight<<"  "<<code<<endl;}
};
void note(int notes[][26], string  target) {	//进行接受整理for (int i = 0; i < 26; i++) {//记录每个字母出现次数notes[0][i] = 97 + i;//将本中第一行都分别记录一个小写字母的编码，}for (char a : target) {//auto是一个占位符(auto a:target)，根据后面的变量，自己推断自己是什么类型,用于变量类型很长for (int i = 0; i < 26; i++) {if (notes[0][i] == a) {notes[1][i]++;break;}}}
}
void chang_shuzu(node target1[],int& j,int notes[][26]) {//创建所需数组cout << "电文中出现的字符及其出现的次数如下" << endl;for (int i = 0; i < 26; i++) {if (notes[1][i] != 0) {cout << (char)notes[0][i] << ":" << notes[1][i] << endl;target1[j].value = (char)notes[0][i];//构建存储字符和权重的数组target1[j].zhi = 1;target1[j++].weight = notes[1][i];}}
}
void maopao(node target1[],int last,int farst) {//运用冒泡排序，将数组根据权重变成递增数组for (int i = farst; i < last-1; i++) {for (int j = farst; j < last- 1; j++) {if (target1[j].weight > target1[j + 1].weight) {node temp;temp = target1[j];target1[j] = target1[j + 1];target1[j + 1] = temp;}}}
}
void change_hafuma(node target1[],int &farst,node target2[],int &s) {//取出数组的前两个，将其投入到创建链表中，后来再将数组前两个删除，存入新结合的树target2[s].weight = target1[farst].weight + target1[farst + 1].weight;target2[s+1]= target1[farst];target2[s+2] = target1[farst + 1];target2[s].left = &target2[s+1];target2[s].right = &target2[s+2];farst++;target1[farst] = target2[s];s = s + 3;
}
void show(node* x,string h,node target3[],int &e) {//h为编码if (x->zhi==1) {//则此时指向的是叶子节点x->code = h;cout << x->value << ':' << h<<endl;target3[e].value = x->value;target3[e++].code = x->code;return;}show(x->left, h + "0", target3,e);show(x->right, h +"1", target3,e);
}
void show2(string target,node target3[],int last) {//展示电文对应编码cout << "电文对应编码为：" << endl;for (char a : target) {for (int i = 0; i < 100; i++) {if (a == target3[i].value) {cout << target3[i].code << " ";break;}}}cout << endl;}
void decode(node target3[],int last){string target;string p="";cout << "输入0-1二进制串（‘e’退出）";cin >> target;while (target!="e") {string he = "";for (char a : target) {he += a;for (int i = 0; i < last; i++) {if (he == target3[i].code) {p += target3[i].value;p += " ";he = "";break;}}}if (he != "") {cout << "编码错误，无法转换！"<<endl<<endl;}else{cout <<"编译转换的电文为：" << p<<endl << endl;}p = "";cout << "输入0-1二进制串（‘e’退出）";cin >> target;}
}
int main() {//接收端int notes[2][26] = { 0 };//令其初始都为0.cout << "输入电文：";string target;cin >> target;//用了for—each循环遍历note(notes,target);node target1[26];//初始记录有效节点node target2[100];//存储哈夫曼树所有节点node target3[26];//记录有效节点,此时其内节点中有每个节点的code值int last = 0;//指向最后一个有效数组元素的后一个int farst = 0;int s = 0;//存哈夫曼节点的数组chang_shuzu(target1, last, notes);//创建数组//构建哈夫曼树int z = 0;int e = 0;while (last - farst != 1) {maopao(target1,last,farst);change_hafuma(target1, farst,target2,s);}node x;x = target1[farst];cout << "电文中出现的字符的哈夫曼编码如下："<<endl;show(&x, "",target3,e);show2(target,target3, last);cout << endl << endl;;decode(target3,last);
}