# 1399. Count Largest Group¶

• Time: $O(n\log n)$
• Space: $O(n)$
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 class Solution { public: int countLargestGroup(int n) { vector count(9 * 4 + 1); for (int i = 1; i <= n; ++i) ++count[getDigitSum(i)]; return ranges::count(count, ranges::max(count)); } private: int getDigitSum(int num) { int digitSum = 0; while (num > 0) { digitSum += num % 10; num /= 10; } return digitSum; } }; 
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 class Solution { public int countLargestGroup(int n) { int[] count = new int[9 * 4 + 1]; for (int i = 1; i <= n; ++i) ++count[getDigitSum(i)]; final int max = Arrays.stream(count).max().getAsInt(); return (int) Arrays.stream(count).filter(c -> c == max).count(); } private int getDigitSum(int num) { int digitSum = 0; while (num > 0) { digitSum += num % 10; num /= 10; } return digitSum; } } 
 1 2 3 4 5 6 7 8 9 class Solution: def countLargestGroup(self, n: int) -> int: count = [0] * (9 * 4 + 1) for i in range(1, n + 1): count[self._getDigitSum(i)] += 1 return count.count(max(count)) def _getDigitSum(self, num: int) -> int: return sum(int(digit) for digit in str(num))