leetcode oj java arrangecoins

一、问题描述

    

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 = 5The coins can form the following rows:¤¤ ¤¤ ¤Because the 3rd row is incomplete, we return 2.

Example 2:

n = 8The coins can form the following rows:¤¤ ¤¤ ¤ ¤¤ ¤Because the 4th row is incomplete, we return 3.

二、思路：

   叠加计数：

三、代码：

public int arrangeCoins(int n) {                int i = 0;        int sum = 0;        for (i = 1; sum <= n - i; i++) {            sum += i;        }        return (i - 1);    }