988. 硬币摆放

class Solution:
    """
    @param n: a non-negative integer
    @return: the total number of full staircase rows that can be formed
    """
    ‘‘‘
    大致思路:
    1.首先阶梯行数是按照1，2,3,4...的顺序进行排放的，那么可以初始化s = 0，while true，s = s + i,直到s大于n
    的时候，返回s - n，即可.
    ‘‘‘
    def arrangeCoins(self,n):
        s = 0
        i = 0
        while True:
            if s > n:
                return i - 1
            i += 1
            s += i