3550. Smallest Index With Digit Sum Equal to Index

class Solution {
    public int smallestIndex(int[] nums) {
        for (int i = 0; i < nums.length; i++) {
            if (digitSum(nums[i]) == i) {
                return i;
            }
        }
        return -1;
    }

    private int digitSum(int n) {
        int sum = 0;
        while (n > 0) {
            sum += n % 10;  // last digit add karo
            n /= 10;        // digit remove karo
        }
        return sum;
    }
}

class Solution:
    def smallestIndex(self, nums):
        for i in range(len(nums)):
            if self.digitSum(nums[i]) == i:
                return i
        return -1

    def digitSum(self, n):
        total = 0

        while n > 0:
            total += n % 10
            n //= 10

        return total

class Solution {
public:
    int smallestIndex(vector<int>& nums) {
        for (int i = 0; i < nums.size(); i++) {
            if (digitSum(nums[i]) == i) {
                return i;
            }
        }
        return -1;
    }

private:
    int digitSum(int n) {
        int sum = 0;

        while (n > 0) {
            sum += n % 10;
            n /= 10;
        }

        return sum;
    }
};

class Solution {
    smallestIndex(nums) {
        for (let i = 0; i < nums.length; i++) {
            if (this.digitSum(nums[i]) === i) {
                return i;
            }
        }

        return -1;
    }

    digitSum(n) {
        let sum = 0;

        while (n > 0) {
            sum += n % 10;
            n = Math.floor(n / 10);
        }

        return sum;
    }
}