hdu1427

速算24点

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 2868    Accepted Submission(s): 685

Problem Description

速算24点相信绝大多数人都玩过。就是随机给你四张牌，包括A(1),2,3,4,5,6,7,8,9,10,J(11),Q(12),K(13)。要求只用'+','-','*','/'运算符以及括号改变运算顺序，使得最终运算结果为24(每个数必须且仅能用一次)。游戏很简单，但遇到无解的情况往往让人很郁闷。你的任务就是针对每一组随机产生的四张牌，判断是否有解。我们另外规定，整个计算过程中都不能出现小数。

 

Input

每组输入数据占一行，给定四张牌。

 

Output

每一组输入数据对应一行输出。如果有解则输出"Yes"，无解则输出"No"。

 

Sample Input

  
  

   
   A 2 3 6
3 3 8 8
  
  

 

Sample Output

  
  

   
   Yes
No
  
  

 

Author

LL

 

#include<iostream>
#include<string>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int a[4];
bool ok = false;

void dfs(int value1, int value2, int cur){
	if(ok){
		return;
	}
	if(cur==3){
		if(value1+value2==24||value1-value2==24||value1*value2==24||(value2&&value1%value2==0&&value1/value2==24)){
			ok = true;
		}
		return;
	}
	dfs(value1+value2, a[cur+1], cur+1);
	dfs(value1, value2+a[cur+1], cur+1);
	dfs(value1-value2, a[cur+1], cur+1);
	dfs(value1, value2-a[cur+1], cur+1);
	dfs(value1*value2, a[cur+1], cur+1);
	dfs(value1, value2*a[cur+1], cur+1);
	if(value2&&value1%value2==0){
		dfs(value1/value2, a[cur+1], cur+1);
	}
	if(a[cur+1]&&value2%a[cur+1]==0){
		dfs(value1, value2/a[cur+1], cur+1);
	}
}

int main(){
	freopen("in.txt", "r", stdin);
	char c[2];
	while(scanf("%s", c)!=EOF){
		if(strlen(c)==2){
			a[0] = 10;
		}else if(c[0]=='A'){
			a[0] = 1;
		}else if(c[0] == 'J'){
			a[0] = 11;
		}else if(c[0]=='Q'){
			a[0] = 12;
		}else if(c[0]=='K'){
			a[0] = 13;
		}else{
			a[0] = int(c[0]-'0');
		}
		for(int i = 1; i<4; i++){
			scanf("%s", c);
			if(strlen(c)==2){
				a[i] = 10;
			}else if(c[0]=='A'){
				a[i] = 1;
			}else if(c[0] == 'J'){
				a[i] = 11;
			}else if(c[0]=='Q'){
				a[i] = 12;
			}else if(c[0]=='K'){
				a[i] = 13;
			}else{
				a[i] = int(c[0]-'0');
			}
		}
	sort(a, a+4);
	ok = false;
	do{
		dfs(a[0],a[1],1);		
	}while(!ok&&next_permutation(a, a+4));
	if(ok){
		printf("Yes\n");
	}else{
		printf("No\n");
	}
	}
	return 0;
}

参考了http://blog.youkuaiyun.com/cambridgeacm/article/details/7751678

http://blog.youkuaiyun.com/kkkwjx/article/details/12939775