66. Plus One

class Solution {
    public int[] plusOne(int[] digits) {
        int n = digits.length, carry = 1, i = 0;
        while(i < n && digits[i] == 9) i++;
        if(i == n)
        {
            int[] re  = new int[n + 1];
            re[0] = 1;
            return re;
        }
        i = n - 1;
        while(i >= 0 && carry > 0)
        {
            int a = digits[i], b = (a + carry) % 10;
            carry = (a + carry) / 10;
            digits[i] = b;
            i--;
        }
        return digits;
    }
}