C语言数据结构之哈夫曼树及哈夫曼编码的实现

代码清单如下：

  1 #pragma once
  2 #include<stdio.h>
  3 #include"stdlib.h"
  4 #include <string.h>
  5 
  6 typedef int ElemType1;
  7 
  8 struct BTreeNode
  9 {
 10     ElemType1 data;
 11     struct BTreeNode* left;
 12     struct BTreeNode* right;
 13 };
 14 //遍历哈夫曼树  
 15 void PrintBTree_int(struct BTreeNode* BT)
 16 {
 17     if (BT != NULL)
 18     {
 19         printf("%d", BT->data);
 20         if (BT->left != NULL || BT->right != NULL)
 21         {
 22             printf(" ( ");
 23             PrintBTree_int(BT->left); //输出左子树  
 24             if (BT->right != NULL)
 25                 printf(" , ");
 26             PrintBTree_int(BT->right); //输出右子树  
 27             printf(" ) ");
 28         }
 29     }
 30 }
 31 
 32 //创建哈夫曼树  
 33 struct BTreeNode* CreateHuffman(ElemType1 a[], int n)
 34 {
 35     int i, j;
 36     struct BTreeNode **b, *q;
 37     b = (BTreeNode **)malloc(n * sizeof(struct BTreeNode));
 38     for (i = 0; i < n; i++)                          //动态内存分配  
 39     {
 40         b[i] = (BTreeNode *)malloc(sizeof(struct BTreeNode));
 41         b[i]->data = a[i];
 42         b[i]->left = b[i]->right = NULL;
 43     }
 44     for (i = 1; i < n; i++)
 45     {
 46         //k1表示森林中具有最小权值的树根结点的下标，k2为次最小的下标  
 47         int k1 = -1, k2;
 48         for (j = 0; j < n; j++)                      //让k1初始指向森林中第一棵树，k2指向第二棵  
 49         {
 50             if (b[j] != NULL && k1 == -1)
 51             {
 52                 k1 = j;
 53                 continue;
 54             }
 55             if (b[j] != NULL)
 56             {
 57                 k2 = j;
 58                 break;
 59             }
 60         }
 61         for (j = k2; j < n; j++)                 //构造最优解  
 62         {
 63             if (b[j] != NULL)
 64             {
 65                 if (b[j]->data < b[k1]->data)
 66                 {
 67                     k2 = k1;
 68                     k1 = j;
 69                 }
 70                 else if (b[j]->data < b[k2]->data)
 71                     k2 = j;
 72             }
 73         }
 74         q = (BTreeNode *)malloc(sizeof(struct BTreeNode));
 75         q->data = b[k1]->data + b[k2]->data;
 76         q->left = b[k1];
 77         q->right = b[k2];
 78 
 79         b[k1] = q;
 80         b[k2] = NULL;
 81     }
 82     free(b);
 83     return q;
 84 }
 85 //计算带权路径  
 86 ElemType WeightPathLength(struct BTreeNode* FBT, int len)//len初始为0  
 87 {
 88     if (FBT == NULL) //空树返回0  
 89         return 0;
 90     else
 91     {
 92         if (FBT->left == NULL && FBT->right == NULL)
 93             return FBT->data * len;
 94         else
 95             return WeightPathLength(FBT->left, len + 1) + WeightPathLength(FBT->right, len + 1);
 96     }
 97 }
 98 
 99 //构造哈夫曼编码  
100 void HuffManCoding(struct BTreeNode* FBT, int len)
101 {
102     static int a[10];
103     if (FBT != NULL)
104     {
105         if (FBT->left == NULL && FBT->right == NULL)
106         {
107             int i;
108             printf("结点的值为%d的编码：", FBT->data);
109             for (i = 0; i < len; i++)
110                 printf("%d", a[i]);
111             printf("\n");
112         }
113         else
114         {
115             a[len] = 0;
116             HuffManCoding(FBT->left, len + 1);
117             a[len] = 1;
118             HuffManCoding(FBT->right, len + 1);
119         }
120     }
121 }