292. Nim Game （取物游戏） by Python

292. Nim Game

题目：

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.

桌子上有一堆石头，一次只能拿1~3个，你先拿，给你石头的数量问你能不能赢

 

答案：

class Solution(object):
    def canWinNim(self, n):
        """
        :type n: int
        :rtype: bool
        """
        if n % 4:
            return True
        else:
            return False

一道脑筋急转弯，想通了会变得很简单，就是如果石头是四的倍数的时候谁先拿x个，另一个就可以拿4-x个，这样到最后剩下4个的时候先拿的就会输掉，
所以只要自己先拿，让石头个数变为4的倍数，就可以让对方输掉，所以只要验证个数是不是4的倍数就可以了。