Count Largest Group

Description

Given an integer n. Each number from 1 to n is grouped according to the sum of its digits. 

Return how many groups have the largest size.

 

Example 1:

Input: n = 13
Output: 4
Explanation: There are 9 groups in total, they are grouped according sum of its digits of numbers from 1 to 13:
[1,10], [2,11], [3,12], [4,13], [5], [6], [7], [8], [9]. There are 4 groups with largest size.

Example 2:

Input: n = 2
Output: 2
Explanation: There are 2 groups [1], [2] of size 1.

Example 3:

Input: n = 15
Output: 6

Example 4:

Input: n = 24
Output: 5

 

Constraints:

• 1 <= n <= 10^4

Solution(javascript)

/**
 * @param {number} n
 * @return {number}
 */
const countLargestGroup = function (n) {
  const sum = (n) => {
    let total = 0
    while (n) {
      total += n % 10
      n = Math.floor(n / 10)
    }
    return total
  }
  const map = {}
  let max = 0
  for (let i = 1; i <= n; i++) {
    const num = sum(i)
    map[num] = (map[num] || 0) + 1
    max = Math.max(map[num], max)
  }
  let maxSize = 0
  for (const currentSize of Object.values(map)) {
    if (currentSize === max) {
      maxSize += 1
    }
  }
  return maxSize
}