HDU 2509 Be the Winner

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Be the Winner

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

 

 

Sample Output

No Yes

 

解：此题是尼姆博弈：

#include<iostream>

using namespace std;

int a[110];

int main()

{

    int n;

    while(scanf("%d",&n)!=EOF)

    {

        int i;

        int s=0;

        int s1=0;

        for(i=0;i<n;i++)

        {

            cin>>a[i];

            s=s^a[i];

            if(a[i]>=2)

            s1++;

        }        

        if(s==0)//奇异局势

        {

            if(s1>=2)cout<<"No"<<endl;    

            else

            cout<<"Yes"<<endl;

        }

        else//非奇异局势

        {

            if(s1>=1)cout<<"Yes"<<endl;    

            else 

            cout<<"No"<<endl;

        }

    }

    

    return 0;    

}