Coding problem · Easy · Basics

Sum of Digits

Easy Algorithms & data structures

Return the sum of the digits of the non-negative integer n.

Example 1

Input: n = 1234
Output: 10

Example 2

Input: n = 0
Output: 0

Hints

Hint 1

n % 10 is the last digit; integer division by 10 removes it.

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Solution and explanation

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Time O(digits) · Space O(1)

Repeatedly add n % 10 and divide n by 10 (integer division) until it reaches 0. Converting to a string and adding characters also works.

Reference solution

function sumOfDigits(n) {
  let total = 0;
  while (n > 0) { total += n % 10; n = Math.floor(n / 10); }
  return total;
}

function sumOfDigits(n: number): number {
  let total = 0;
  while (n > 0) { total += n % 10; n = Math.floor(n / 10); }
  return total;
}

def sum_of_digits(n: int) -> int:
    return sum(int(ch) for ch in str(n))

<?php

function sumOfDigits(int $n): int
{
    return array_sum(str_split((string) $n));
}

class Solution {
    public int sumOfDigits(int n) {
        int total = 0;
        while (n > 0) { total += n % 10; n /= 10; }
        return total;
    }
}

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