霍夫曼树建树初步

漏掉了huffman树,赶紧来一发.

 

huffman:构建最小带权二叉树,算法思想为贪心.

 

hdu1053

#include <algorithm>
#include <functional>
using namespace std;

struct tree
{
    tree* prent;
    tree* l;
    tree* r;
    int val;
    char chr;
    tree()
    {
        this->val=0;
        this->chr=0;
        this->l=NULL;
        this->r=NULL;
    }    
};

int sortcmp(const void *p1, const void *p2)
{
    tree** t1=(tree**)p1;
    tree** t2=(tree**)p2;
    return (*t1)->val-(*t2)->val;
}

tree* create(int val,char chr,tree* l,tree* r)
{
    tree* t = new tree();
    t->val=val;
    t->chr=chr;
    t->l=l;
    t->r=r;
    return t;
}

void del(tree* t)
{
    if(t->l)
    {
        del(t->l);
    }
    
    if(t->r)
    {
        del(t->r);
    }
    
    delete t;
}

int sub(tree* t,int* h,int c)
{
    c++;
    int sum=0;
    if(t->l!=NULL)
    {
        sum+=sub(t->l,h,c);
    }
    
    if(t->r!=NULL)
    {
        sum+=sub(t->r,h,c);
    }
    if(t->chr>0);
    {
        sum+=c*h[t->chr];
    }
    return sum;
}

int main()
{
    char str[1024]={0};
    while(scanf("%s",str)!=EOF && strcmp(str,"END")!=0)
    {
        int huff[255]={0};
        for(int i=0;i<strlen(str);i++)
        {
            huff[str[i]]++;
        }
        tree* q[10240];
        int h=0,f=0;
        for(int i=0;i<255;i++)
        {
            if(huff[i])
            {
                q[f++]=create(huff[i],i,NULL,NULL);
            }
        }
        while(f-h>1)
        {
            qsort(&q[h],f-h,sizeof(tree*),sortcmp);    
            q[f++]=create(q[h]->val+q[h+1]->val,0,q[h],q[h+1]);
            h+=2;
        }
        int newlen = sub(q[f-1],huff,-1);
        if(newlen==0)
        {
            newlen=strlen(str);//hack
        }
        printf("%d %d %.1lf\n",strlen(str)*8,newlen,strlen(str)*8.0/newlen);
        del(q[f-1]);
        memset(str,0,sizeof(str));
    }
    //system("pause");
    return 0;
}