Arranging Coins

Description

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.

Solution(javascript)

/**
 * @param {number} n
 * @return {number}
 */
const arrangeCoins = (n) => {
  let sum = 0
  let counter = 0
  while (sum < n) {
    counter += 1
    sum += counter
  }
  return sum === n ? counter: counter - 1
}