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.

Hint:

1. If there are 5 stones in the heap, could you figure out a way to remove the stones such that you will always be the winner?

解析：

A先摸，总数为1，2，3，A胜；为4，败；总数再大，进入相同循环：只要在A摸完一次后让剩下的数目为4的倍数，A必胜，如5，6，7，A胜，8，B胜……

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