hdu 1427 速算24点(next_permutation 搜索)

题意：给出四张扑克牌 问能否算出24

思路：http://blog.csdn.net/xingyeyongheng/article/details/11137631

        其实这题只有两种运算顺序

         1（a@b）@c@d

         2 (a@b)@(c@d)

         所以只需要把数字和运算符全排列遍历一边就可以判断出结果

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int num[5],ok;
const int INF=100000;
int change_num(char a)
{
    if(a=='A') return 1;
    else if(a=='J') return 11;
    else if(a=='Q') return 12;
    else if(a=='K') return 13;
    if(a=='1') return 10;
    else return a-'0';
}
int fun2(int a,int op,int b)
{
    if(op==0)
    {
        return a+b;
    }
    else if(op==1)
    {
        return a-b;
    }
    else if(op==2)
    {
        return a*b;
    }
    else if(op==3)
    {
        if(b==0||a%b!=0 )return INF;
        return a/b;
    }
}
void fun1(int i,int j,int k)
{
    if(ok==1) return;
    int t1,t2,t3;
    t1=fun2(num[0],i,num[1]);
    if(t1!=INF)
    {
        t2=fun2(t1,j,num[2]);
        if(t2!=INF)
        {
            t3=fun2(t2,k,num[3]);

            if(t3==24||t3==-24) ok=1;
        }
    }
    if(ok==0)
    {
        t1=fun2(num[0],i,num[1]);
        t2=fun2(num[2],j,num[3]);
        if(t1!=INF&&t2!=INF)
        {
                t3=fun2(t1,k,t2);
                if(t3==24||t3==-24) ok=1;
        }
    }
}
int main()
{
    int i,j,k;
    char temp[5];
    while(scanf("%s",temp)!=EOF)
    {
        ok=0;
        num[0]=change_num(temp[0]);
        for(i=1;i<=3;i++)
        {
            scanf("%s",temp);
            num[i]=change_num(temp[0]);
        }
        sort(num,num+4);
        do
        {
           for(i=0;i<4;i++)
           {
               for(j=0;j<4;j++)
               {
                   for(k=0;k<4;k++)
                   {
                      fun1(i,j,k);
                   }
               }
           }
           if(ok==1) break;
        }while (next_permutation(num,num+4));
        if(ok==1) printf("Yes
");
        else printf("No
");
    }
    return 0;
}