构造哈弗曼树-蒲公英云

构造哈弗曼树

#include<iostream>
using namespace std;
struct HTreeNode{
    int weight;
    HTreeNode* parent;
    HTreeNode* lchild;
    HTreeNode* rchild;
};
HTreeNode* CreatHuffmanTree(int *w, int n)
{
    int m = 2 * n - 1;
    HTreeNode* HT = new HTreeNode[m];
    for (int i = 0; i < n; ++i){
        HT[i].weight = w[i]; HT[i].parent = HT[i].lchild = HT[i].rchild = NULL;
    }
    for (int i = n; i < m; ++i){
        HT[i].weight = 0; HT[i].parent = HT[i].lchild = HT[i].rchild = NULL;
    }
    int m1 = -1, m2;
    for (int i = n; i < m; ++i)
    {
        int m1 = -1, m2;
        for (int j = 0; j < i; ++j)
        {
            if (!HT[j].parent&&m1 == -1){ m1 = j; continue; }
            if (!HT[j].parent){ m2 = j; break; }
        }
        for (int j = m2; j < i; ++j)
        {
            if (!HT[j].parent)
            {
                if (HT[j].weight < HT[m1].weight){ m2 = m1; m1 = j; }
                else if (HT[j].weight < HT[m2].weight)m2 = j;
            }    
        }
        HT[i].weight = HT[m1].weight + HT[m2].weight;
        HT[i].lchild = &HT[m1]; HT[i].rchild = &HT[m2];
        HT[m1].parent = &HT[i]; HT[m2].parent = &HT[i];
    }
    return &HT[m - 1];
}
void PreOrderTraverse(HTreeNode* T)
{
    if (T)
    {
        cout << T->weight << " ";
        PreOrderTraverse(T->lchild);
        PreOrderTraverse(T->rchild);
    }
}
void main()
{
    int w[] = { 7, 5, 2, 4 };
    HTreeNode* HT = CreatHuffmanTree(w, sizeof(w) / sizeof(int));
    PreOrderTraverse(HT);
}