README.md

1399. Count Largest Group

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

Solutions (Python)

1. Solution

class Solution:
    def countLargestGroup(self, n: int) -> int:
        counter = {}

        for i in range(1, n + 1):
            digits_sum = sum(map(int, str(i)))
            if digits_sum not in counter:
                counter[digits_sum] = 0
            counter[digits_sum] += 1

        largest_size = max(counter.values())

        return sum(map(lambda x: x == largest_size, counter.values()))