Leetcode题目：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.

注意到：（1）当给定的n小于4的时候，可以确保自己获胜。（2）当为4（或4的整数倍）的时候，自己一定输。（3）不是4的整数倍时，能够保证赢。

代码如下：

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

其实可以把第一个判断条件略去，后面的判断条件包含了它的。