假设有n个人，则第m个人出局后，从第m+1个人开始重新计数，所以m+1映射成0.
得到函数：
n = 1：f = 0
n > 1: f(n,m) = (f(n-1,m) + m) %n

class Solution:
    def LastRemaining_Solution(self, n, m):
        # write code here
        if n < 1 or m < 1:
            return -1
        last = 0
        for i in range(2,n+1):
            last =  (last + m) % i
        return last