3754. Concatenate Non-Zero Digits and Multiply by Sum I

class Solution {
    public long sumAndMultiply(int n) {
        long x = 0;
        long sum = 0;

        if (n == 0) return 0;

        String s = String.valueOf(n);

        for (char ch : s.toCharArray()) {
            if (ch != '0') {
                int digit = ch - '0';
                x = x * 10 + digit;
                sum += digit;
            }
        }

        return x * sum;
    }
}

class Solution:
    def sumAndMultiply(self, n: int) -> int:
        if n == 0:
            return 0

        x = 0
        digit_sum = 0

        for ch in str(n):
            if ch != '0':
                digit = int(ch)
                x = x * 10 + digit
                digit_sum += digit

        return x * digit_sum

class Solution {
public:
    long long sumAndMultiply(int n) {
        if (n == 0) return 0;

        long long x = 0;
        long long sum = 0;

        string s = to_string(n);

        for (char ch : s) {
            if (ch != '0') {
                int digit = ch - '0';
                x = x * 10 + digit;
                sum += digit;
            }
        }

        return x * sum;
    }
};

/**
 * @param {number} n
 * @return {bigint}
 */
var sumAndMultiply = function(n) {
    if (n === 0) return 0n;

    let x = 0n;
    let sum = 0n;

    const s = n.toString();

    for (const ch of s) {
        if (ch !== '0') {
            const digit = BigInt(ch);
            x = x * 10n + digit;
            sum += digit;
        }
    }

    return x * sum;
};