【leetcode】441. Arranging Coins【E】

You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins.

Given n, find the total number of full staircase rows that can be formed.

n is a non-negative integer and fits within the range of a 32-bit signed integer.

Example 1:

n = 5

The coins can form the following rows:
¤
¤ ¤
¤ ¤

Because the 3rd row is incomplete, we return 2.

Example 2:

n = 8

The coins can form the following rows:
¤
¤ ¤
¤ ¤ ¤
¤ ¤

Because the 4th row is incomplete, we return 3.

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這道題簡直不能更簡單，可不知道爲啥通過率竟然這麼低。。

其實就是

1+2+……+k < n, 求最大的k是多少

class Solution(object):
    def arrangeCoins(self, n):
        res = 0
        while n > res:
            res += 1
            n -= res
            #print res,n
        return res