39-实战演练

2.6.5　实战演练

//program 2-6
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdlib>
using namespace std;
#define MAXBIT    100
#define MAXVALUE  10000
#define MAXLEAF   30
#define MAXNODE   MAXLEAF*2 -1
typedef struct
{
    double weight;
    int parent;
    int lchild;
    int rchild;
    char value;
} HNodeType;        /* 结点结构体 */
typedef struct
{
    int bit[MAXBIT];
    int start;
} HCodeType;        /* 编码结构体 */
HNodeType HuffNode[MAXNODE]; /* 定义一个结点结构体数组 */
HCodeType HuffCode[MAXLEAF];/* 定义一个编码结构体数组*/
/* 构造哈夫曼树 */
void HuffmanTree (HNodeType HuffNode[MAXNODE],  int n)
{
    /* i、j： 循环变量，m1、m2：构造哈夫曼树不同过程中两个最小权值结点的权值，
       x1、x2：构造哈夫曼树不同过程中两个最小权值结点在数组中的序号。
    */
    int i, j, x1, x2;
    double m1,m2;
    /* 初始化存放哈夫曼树数组 HuffNode[] 中的结点 */
    for (i=0; i<2*n-1; i++)
    {
         HuffNode[i].weight = 0;//权值
         HuffNode[i].parent =-1;
         HuffNode[i].lchild =-1;
         HuffNode[i].rchild =-1;
    }
    /* 输入 n 个叶子结点的权值 */
    for (i=0; i<n; i++)
    {
         cout<<"Please input value and weight of leaf node "<<i + 1<<endl;
         cin>>HuffNode[i].value>>HuffNode[i].weight;
    }
    /* 构造 Huffman 树 */
    for (i=0; i<n-1; i++)
    {//执行n-1次合并
         m1=m2=MAXVALUE;
         /* m1、m2中存放两个无父结点且结点权值最小的两个结点 */
         x1=x2=0;
         /* 找出所有结点中权值最小、无父结点的两个结点，并合并之为一棵二叉树 */
         for (j=0; j<n+i; j++)
         {
              if (HuffNode[j].weight < m1 && HuffNode[j].parent==-1)
              {
                  m2 = m1;
                  x2 = x1;
                  m1 = HuffNode[j].weight;
                  x1 = j;
              }
              else if (HuffNode[j].weight < m2 && HuffNode[j].parent==-1)
              {
                  m2=HuffNode[j].weight;
                  x2=j;
              }
         }
         /* 设置找到的两个子结点 x1、x2 的父结点信息 */
         HuffNode[x1].parent  = n+i;
         HuffNode[x2].parent  = n+i;
         HuffNode[n+i].weight = m1+m2;
         HuffNode[n+i].lchild = x1;
         HuffNode[n+i].rchild = x2;
         cout<<"x1.weight and x2.weight in round "<<i+1<<"\t"<<HuffNode[x1]. weight<<"\t"<<HuffNode[x2].weight<<endl; /* 用于测试 */
    }
}
/* 哈夫曼树编码 */
void HuffmanCode(HCodeType HuffCode[MAXLEAF],  int n)
{
    HCodeType cd;       /* 定义一个临时变量来存放求解编码时的信息 */
    int i,j,c,p;
    for(i = 0;i < n; i++)
    {
        cd.start = n-1;
        c = i;
        p = HuffNode[c].parent;
        while(p != -1)
        {
            if(HuffNode[p].lchild == c)
                cd.bit[cd.start] = 0;
            else
                cd.bit[cd.start] = 1;
            cd.start--;        /* 求编码的低一位 */
            c = p;
            p = HuffNode[c].parent;    /* 设置下一循环条件 */
        }
        /* 把叶子结点的编码信息从临时编码cd中复制出来，放入编码结构体数组 */
        for (j=cd.start+1; j<n; j++)
           HuffCode[i].bit[j] = cd.bit[j];
        HuffCode[i].start = cd.start;
    }
}
int main()
{
    int i,j,n;
    cout<<"Please input n："<<endl;
    cin>>n;
    HuffmanTree (HuffNode, n);  /* 构造哈夫曼树 */
    HuffmanCode(HuffCode, n);  /* 哈夫曼树编码 */
    /* 输出已保存好的所有存在编码的哈夫曼编码 */
    for(i = 0;i < n;i++)
    {
        cout<<HuffNode[i].value<<": Huffman code is: ";
        for(j=HuffCode[i].start+1; j < n; j++)
            cout<<HuffCode[i].bit[j];
        cout<<endl;
    }
    return 0;
}

算法实现和测试

（1）运行环境

Code::Blocks

（2）输入

Please input n：
6
Please input value and weight of leaf node 1
a 0.05
Please input value and weight of leaf node 2
b 0.32
Please input value and weight of leaf node 3
c 0.18
Please input value and weight of leaf node 4
d 0.07
Please input value and weight of leaf node 5
e 0.25
Please input value and weight of leaf node 6
f 0.13

（3）输出

x1.weight and x2.weight in round 1      0.05    0.07
x1.weight and x2.weight in round 2      0.12    0.13
x1.weight and x2.weight in round 3      0.18    0.25
x1.weight and x2.weight in round 4      0.25    0.32
x1.weight and x2.weight in round 5      0.43    0.57
a: Huffman code is: 1000
b: Huffman code is: 11
c: Huffman code is: 00
d: Huffman code is: 1001
e: Huffman code is: 01
f: Huffman code is: 101