leetcode_java_nim game

问题如下:

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.

问题意思是如何能够必赢。

分析：5，6，7下可以赢，8的情况下赢不确定，对手足够聪明的话他可以赢。9，10，11由于自己先选，则可以让他面对8这个情况。又必赢。12下对手足够聪明他可以赢。13，14，15可以让他面对12这个情况，自己赢。

...

代码如下：public class Solution {
public boolean canWinNim(int n) {
if((n&3)>0)
return true;
return false;
}
}如果能够被4整除的话，那么就可以赢。上述代码就是通过位运算来判断是否可以被4整除。

该方案运行时间是：



有更快的方法请拍砖～