哈夫曼树--贪心算法

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#include<iostream>#include<cstdio>#include<cstring>using namespace std;#define N 10    // 带编码字符的个数，即树中叶结点的最大个数#define M 19    // 树中总的结点数目class HTNode{   // 树中结点的结构public:    unsigned int weight;    unsigned int parent,lchild,rchild;};class HTCode{public:    char data;      // 待编码的字符    int weight;     // 字符的权值    char code[N];   // 字符的编码};void Init(HTCode hc[], int *n){// 初始化，读入待编码字符的个数n，从键盘输入n个字符和n个权值    cout<<"输入字符个数"<<endl;    cin>>*n;    cout<<"输入字符"<<endl;    for(int i = 1; i <= *n; ++i)        cin >> hc[i].data;    cout << "输入权值" << endl;        for(int i = 1; i <= *n; ++i)        cin >> hc[i].weight;}void Select(HTNode ht[], int k, int *s1, int *s2){// ht[1...k]中选择parent为0，并且weight最小的两个结点，其序号由指针变量s1，s2指示    int i;    for(i=1; i<=k && ht[i].parent != 0; ++i);    *s1 = i;    for(i=1; i<=k; ++i){        if(ht[i].parent==0 && ht[i].weight<=ht[*s1].weight)            *s1 = i;    }//找到最小的节点    for(i=1; i<=k; ++i){        if(ht[i].parent==0 && i!=*s1)            break;    }    *s2 = i;    for(i=1; i<=k; ++i){        if(ht[i].parent==0 && i!=*s1 && ht[i].weight<=ht[*s2].weight)            *s2 = i;    }}void HuffmanCoding(HTNode ht[],HTCode hc[],int n){// 构造Huffman树ht，并求出n个字符的编码    char cd[N];    int m,c,f,s1,s2,start;    m = 2*n-1;    for(int i=1; i<=m; ++i){        if(i <= n)            ht[i].weight = hc[i].weight;        else            ht[i].parent = 0;        ht[i].parent = ht[i].lchild = ht[i].rchild = 0;    }    for(int i=n+1; i<=m; ++i){        Select(ht, i-1, &s1, &s2);        ht[s1].parent = i;        ht[s2].parent = i;        ht[i].lchild = s1;        ht[i].rchild = s2;        ht[i].weight = ht[s1].weight+ht[s2].weight;    }    cd[n-1] = '\0';    for(int i=1; i<=n; ++i){        start = n-1;        for(c=i,f=ht[i].parent; f; c=f,f=ht[f].parent){            if(ht[f].lchild == c)//左为0，右为1                cd[--start] = '0';            else                cd[--start] = '1';        }        strcpy(hc[i].code, &cd[start]);    }}int main(){    int i,n;    HTNode ht[M+1];    HTCode hc[N+1];    Init(hc, &n);     // 初始化    HuffmanCoding(ht,hc,n);   // 构造Huffman树，并形成字符的编码    for(i=1; i<=n; ++i)        cout<<hc[i].data<<"---"<<hc[i].code<<endl;    cout<<endl;    return 0;}
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