哈夫曼树

声明：图片及内容基于https://www.bilibili.com/video/BV1MK411j7CR?from=articleDetail

特点

构造过程

存储结构

代码

#include<iostream>
#include<vector> 
#include <limits.h>
#include<iomanip>
using namespace std;
struct element {
    int weight;
    int lchild, rchild, parent;
};
void select(element huffTree[], int n, int& s1, int& s2);  //传递引用
void HuffmanTree(element huffTree[], int w[], int n) {
    for (int i = 0; i < 2 * n - 1; i++) {     //初始化哈夫曼树 注意2*n-1给结点
        huffTree[i].lchild = -1;
        huffTree[i].parent = -1;
        huffTree[i].rchild = -1;
    }
    for (int i = 0; i < n; i++) {
        huffTree[i].weight = w[i];  //复制权值 
    }
    for (int k = n; k < 2 * n - 1; k++) {
        int i1, i2;          //i1最小，i2次小 为下标 
        select(huffTree, k, i1, i2);    //注意这里必须传k，k是个变量，代表已经有k个结点作为待选数据，且每次k都增加
        huffTree[k].weight = huffTree[i1].weight + huffTree[i2].weight;
        huffTree[i1].parent = k;
        huffTree[i2].parent = k;
        huffTree[k].lchild = i1;
        huffTree[k].rchild = i2;
        cout << "最小下标：" << i1 << " 次小下标：" << i2 << endl;
    }
}
void select(element huffTree[], int n, int& s1, int& s2) {   //传递引用
    int i;
    s1 = s2 = 0;
    int min1 = INT_MAX;//最小值，INT_MAX在<limits.h>中定义的，INT_MAX是最大值2^31-1
    int min2 = INT_MAX;//次小值，找最小值就默认初始值为最大值

    for (i = 0; i < n; ++i)
    {
        if (huffTree[i].parent == -1)
        {//筛选没有父节点的最小和次小权值下标
            if (huffTree[i].weight < min1)
            {//如果比最小值小
                min2 = min1;       //min1不是最小值了，成为次小值，赋给min2
                s2 = s1;
                min1 = huffTree[i].weight;   //把新的最小值赋给min1
                s1 = i; 
            }
            else if ((huffTree[i].weight >= min1) && (huffTree[i].weight < min2))
            {//如果大于等于最小值，且小于次小值
                min2 = huffTree[i].weight;    //更新最小值
                s2 = i;
            }
            else
            {//如果大于次小值，则什么都不做
                ;
            }
        }
    }

}
int main() {
    int n;   //结点个数
    cout << "请输入结点个数：" << endl;
    cin >> n;
    int w[100];
    cout << "请输入" << n << "个权值" << endl;
    for (int i = 0; i < n; i++) {     //初始化权值 
        int t;
        cin >> t;
        w[i] = t;
    }
    struct element huffTree[100];
    HuffmanTree(huffTree, w, n);
    cout << "打印哈夫曼树的数组内容："<<endl;
    cout << "weight parent lchild rchild" << endl;
    for (int i = 0; i < 2*n-1; i++) {
        cout << setw(2) << huffTree[i].weight << "      " << setw(2) << huffTree[i].parent
            << "      " << setw(2) << huffTree[i].lchild << "      " << setw(2) << huffTree[i].rchild << endl;
    }
    return 0;
}