Question

Link : https://leetcode.com/problems/nim-game/

You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 stones. The one who removes the last stone will be the winner. You will take the first turn to remove the stones.

Both of you are very clever and have optimal strategies for the game. Write a function to determine whether you can win the game given the number of stones in the heap.

For example, if there are 4 stones in the heap, then you will never win the game: no matter 1, 2, or 3 stones you remove, the last stone will always be removed by your friend.

Code

其实这个题目我是列了前12的数据后发现的，实际上A先手，B后手，如果A想要赢也就是说在若干次取完石子后，如果可以出现剩余四个石头的情况，则A必能赢。= =。然后我神奇的猜想是不是和取余有关。。希望有大神解释一下。。
（C++ : 0ms）…看到这个我吓尿了…

class Solution {
public:
    bool canWinNim(int n) {
        if(n == 0)
            return false;
        else if(n <= 3)
            return true;
        return n % 4;
    }
};