plus-one.ts

function plusOne(digits: number[]): number[] {
    let carry = 1;

    for (let i = digits.length - 1; i >= 0; i--) {
        if (carry === 0) {
            return digits;
        }

        const sum = digits[i] + carry;

        if (sum === 10) {
            carry = 1;
            digits[i] = 0;
        } else {
            carry = 0;
            digits[i] = sum;
        }
    }

    if (carry > 0) {
        digits.unshift(1);
    }

    return digits;
};