首页 > ACM题库 > HDU-杭电 > HDU 1907 John-博弈论-[解题报告] C++
2013
12-23

HDU 1907 John-博弈论-[解题报告] C++

John

问题描述 :

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.

输入:

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

输出:

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

样例输入:

2
3
3 5 1
1
1

样例输出:

John
Brother

n堆石子,最后一个取完的人输。

Nimm博弈,全是1的时候,特判,数1的个数,奇数输,偶数赢了。

证明过程见:http://blog.csdn.net/acm_cxlove/article/details/7854530

代码如下:

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;
int main()
{
#ifdef test
    freopen("input.txt", "r", stdin);
#endif
    int t, num;
    scanf("%d",&t);
    while(t--)
    {
        int ans = 0, flag = 0, m;
        scanf("%d", &num);
        for(int i=0; i<num; i++)
        {
            scanf("%d",&m);
            ans ^= m;
            if(m != 1)
                flag=1;
        }
        if(flag)
        {
            if(ans == 0)
                printf("Brother\n");
            else
                printf("John\n");
        }
        else
        {
            if(num%2 != 0)
                printf("Brother\n");
            else
                printf("John\n");
        }
    }
    return 0;
}

解题报告转自:http://blog.csdn.net/goomaple/article/details/8884244


  1. 题本身没错,但是HDOJ放题目的时候,前面有个题目解释了什么是XXX定律。
    这里直接放了这个题目,肯定没几个人明白是干啥