用C语言实现哈夫曼树

//哈夫曼树C语言实现#include <stdio.h>#include <stdlib.h>typedef struct HuffmanNode{    char letter;//存储的字符，叶节点为字母，非叶节点为#    struct HuffmanNode *parent;//父亲结点    int code;//如果为父亲结点的左孩子，则为0，右孩子为1}HuffmanNode;typedef struct HeapNode{    int rate;//出现频率    HuffmanNode *node;//对应于哈夫曼树中的结点}HeapNode;/*------------------全局变量----------------------*/int heapSize;//堆大小int num;//记录字符数量HeapNode *heap;//堆数组char *letter;//字符数组int *rate;//字符出现频率HuffmanNode **array; //记录叶节点的数组，打印编码的时候可以从叶结点回溯向上char ch;/*----------------------函数声明-------------------------*/void init(int numOfLetters);//初始化变量void input();//输入数组int parent(int i);//求父节点int left(int i);//求左孩子int right(int i);//求右孩子void swap(int i,int j);//交换函数void heapIfy(int i,int localHeapSize);//维持堆性质函数，使用前提为左右子树均为最小堆void buildHeap();//初始化堆HeapNode* extractMin();//去掉并返回堆中最小的元素void heapInsert(int rate,HuffmanNode *p);//向堆中插入数据（前提：堆已经初始化）HuffmanNode* buildTree();//构造哈夫曼树void display();//显示函数void backPrint(HuffmanNode *p,HuffmanNode *root);//从叶节点回溯打印编码code/*----------------------函数实现-------------------------*/void init(int numOfLetters){    heapSize=numOfLetters;//堆大小初始化为字母数    num=numOfLetters;//记录字符数量    heap=(HeapNode*)malloc((numOfLetters+1)*sizeof(HeapNode));//分配堆空间，最多只需要字符的个数，因为合并过程中删除两个，插入一个    letter=(char*)malloc((numOfLetters+1)*sizeof(char));//用于存储字符    rate=(int *)malloc((numOfLetters+1)*sizeof(int));//用于存储字符出现频率    array=(HuffmanNode **)malloc((numOfLetters+1)*sizeof(HuffmanNode));//记录叶节点的数组，打印编码的时候可以从叶结点回溯向上}void input(){    int i=1;    while(i<=heapSize)    {        printf("输入第%d个字符\n",i);        scanf("%c",&letter[i]);ch=getchar();        printf("输入第%d个字符的频度\n",i);        scanf("%d",&rate[i]);ch=getchar();        //向堆中插入各个结点        heap[i].rate=rate[i];        heap[i].node=(HuffmanNode *)malloc(sizeof(HuffmanNode));        array[i]=heap[i].node;        heap[i].node->parent=NULL;        heap[i].node->letter=letter[i];        i++;    }}int parent(int i){    return i/2;}int left(int i){    return 2*i;}int right(int i){    return 2*i+1;}void swap(int i,int j) //交换结构体数组，需要交换结构体内数据{    int rate;    HuffmanNode *p;    rate=heap[i].rate;    p=heap[i].node;    heap[i].rate=heap[j].rate;    heap[i].node=heap[j].node;    heap[j].rate=rate;    heap[j].node=p;}void heapIfy(int i,int localHeapSize)//维持堆性质函数，使用前提为左右子树均为最小堆{    int l=left(i);    int r=right(i);    int least=i;    //找出heap成员rate 的i,left(i),right(i)的最小值    if(l<=localHeapSize&&heap[least].rate>heap[l].rate)    {        least=l;    }    if(r<=localHeapSize&&heap[least].rate>heap[r].rate)    {        least=r;    }    if(least!=i)    {        swap(i,least);        heapIfy(least,localHeapSize);    }}void buildHeap()//初始化堆{    int i=0;    for(i=heapSize/2;i>=1;i--)    {        heapIfy(i,heapSize);    }}HeapNode* extractMin(){    if(heapSize>=1)    {      HeapNode *min;      swap(1,heapSize);      min=&heap[heapSize];      --heapSize;      heapIfy(1,heapSize);      return min;    }    else    {        printf("堆中没有元素");        return NULL;    }}void heapInsert(int rate,HuffmanNode *p){    ++heapSize;    int i=heapSize;    while(i>1&&heap[parent(i)].rate>rate)    {        heap[i].rate=heap[parent(i)].rate;        heap[i].node=heap[parent(i)].node;        i=parent(i);    }    heap[i].rate=rate;    heap[i].node=p;}HuffmanNode* buildTree(){    buildHeap();//初始化堆    HeapNode *p;//用于临时存储最小堆结点    HeapNode *q;//用于临时存储次小堆结点    int count=heapSize;    int i;    for(i=1;i<=count-1;i++)    {        HuffmanNode *tree=(HuffmanNode*)malloc(sizeof(HuffmanNode));//生成内结点        tree->letter='#';//内结点的字符记作#，没有实际意义        p=extractMin();        q=extractMin();        p->node->parent=tree;        p->node->code=0;        q->node->parent=tree;        q->node->code=1;        //printf("%c:%d",p->node->letter,p->node->code);        //printf("\n"); printf("%c:%d",q->node->letter,q->node->code);   printf("\n");//测试        heapInsert(p->rate+q->rate,tree);//插入堆中    }    return extractMin()->node;}void display(){    HuffmanNode*p=buildTree();////哈夫曼树的根节点地址    int i=1;    while(i<=num)    {        printf("%c:",array[i]->letter);        backPrint(array[i],p);        printf("\n");        i++;    }}void backPrint(HuffmanNode *p,HuffmanNode *root){    if(p!=root)    {        backPrint(p->parent,root);        printf("%d",p->code);//printf("++++");//测试    }}int main(int argc ,char* argv[]){    int number;    printf("输入的字符个数为：\n");    scanf("%d",&number);    ch=getchar();    init(number);    input();    display();    system("PAUSE");    return 0;}