題目：
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.
答案：
public:
bool canWinNim(int n) {
if (n < 4) {
return true;
}
return n % 4 != 0;
}
};
解析：
主要是將題意轉(zhuǎn)化一下，很快發(fā)現(xiàn)只要是4的倍數(shù)梧躺，都不可能會贏铺根。（如果對方不蠢的話）刻伊。想贏的話，只要將剩下的石頭個數(shù)保持在4的倍數(shù)就可以了蔚袍。
