441. Arranging Coins*

441. Arranging Coins*

https://leetcode.com/problems/arranging-coins/

题目描述

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 = 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.

C++ 实现 1

class Solution {
public:
    int arrangeCoins(int n) {
        long long res = 0;
        long long sum = 0;
        long long k = 0;
        while (true) {
            sum += ++ k;
            if (sum > n) break;
            res ++;
        }
        return res;
    }
};