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.
思路： 和朋友玩游戏，有一堆石头，你先拿石头，你可以一次拿走1-3块石头，谁先拿到最后一块就谁赢，写一个函数，根据初始石头的数量，返回你能不能赢。能赢返回1，不能赢返回0。其实就是如果石头数量不是4的的位数，就能赢，求余数问题。
代码：
class Solution { public: bool canWinNim(int n) { if(n<=0){ return -1; } else if(n%4!=0){ return 1; } else{ return 0; } } };