HDOJ 2509 Be the Winner （反尼姆博弈）

Be the Winner

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 2718    Accepted Submission(s): 1487

Problem Description

Let's consider m apples divided into n groups. Each group contains no more than 100 apples, arranged in a line. You can take any number of consecutive apples at one time.
For example "@@@" can be turned into "@@" or "@" or "@ @"(two piles). two people get apples one after another and the one who takes the last is
the loser. Fra wants to know in which situations he can win by playing strategies (that is, no matter what action the rival takes, fra will win).

 

Input

You will be given several cases. Each test case begins with a single number n (1 <= n <= 100), followed by a line with n numbers, the number of apples in each pile. There is a blank line between cases.

 

Output

If a winning strategies can be found, print a single line with "Yes", otherwise print "No".

 

Sample Input

   
   
   
   

    
    
    
    2
2 2
1
3
   
   
   
   

 

尼姆博弈的一个变形，需要注意的点在代码中标记出来了

Sample Output

   
   
   
   

    
    
    
    No
Yes

ac代码：

    
    
    
    
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<iostream>
#include<algorithm>
#define MAXN 100010
#define MAX(a,b) a>b?a:b
using namespace std;
int main()
{
	int n,i,num;
	while(scanf("%d",&n)!=EOF)
	{
		int ans=0;
		int bz=0;
		for(i=0;i<n;i++)
		{
			scanf("%d",&num);
			if(num>1)//注意
			bz=1;
			ans^=num;
		}
		if(bz==0)
		{
			if(ans)//其实也可以不用检验ans
			{
				printf(n%2?"No\n":"Yes\n");//注意
			}
			else
			printf("Yes\n");
		}
		else
		{
			printf(ans?"Yes\n":"No\n");
		}
	}
	return 0;
}