HDU 1907 John (Nim博弈)

问题描述：
Problem Description
Little John is playing very funny game with his younger brother. There is one big box filled with M&Ms of different colors. At first John has to eat several M&Ms of the same color. Then his opponent has to make a turn. And so on. Please note that each player has to eat at least one M&M during his turn. If John (or his brother) will eat the last M&M from the box he will be considered as a looser and he will have to buy a new candy box.

Both of players are using optimal game strategy. John starts first always. You will be given information about M&Ms and your task is to determine a winner of such a beautiful game.

Input
The first line of input will contain a single integer T – the number of test cases. Next T pairs of lines will describe tests in a following format. The first line of each test will contain an integer N – the amount of different M&M colors in a box. Next line will contain N integers Ai, separated by spaces – amount of M&Ms of i-th color.

Constraints:
1 <= T <= 474,
1 <= N <= 47,
1 <= Ai <= 4747

Output
Output T lines each of them containing information about game winner. Print “John” if John will win the game or “Brother” in other case.

Sample Input
2
3
3 5 1
1
1

Sample Output
John
Brother

大致题意：
nim博弈。
n堆石子。
一次从一堆中取若干个。至少取一个，无上限。
直接异或。讨论一下全是1的情况。

ac代码：

#include<bits/stdc++.h>using namespace std;int main(){    int T,n,m,a,ans,flag;    cin>>T;    while(T--)    {        cin>>n;        ans=0;        flag=0;        for(int i=0;i<n;i++)        {            cin>>a;            ans^=a;            if(a>1)                flag=1;        }        if(flag)        {            if(ans)                cout<<"John"<<endl;            else                cout<<"Brother"<<endl;        }        else        {            if(n&1)                cout<<"Brother"<<endl;            else                cout<<"John"<<endl;        }    }}