public class PlusOne {

public int[] plusOne(int[] digits) {

int len = digits.length;

int[] result = new int[len + 1];

if (len == 0) {

return digits;

}

int carry = 0;

if (digits[len - 1] < 9) {

digits[len - 1] += 1;

return digits;

}

else {

digits[len - 1] = 0;

carry = 1;

}

for (int i = len - 2; i >=0; i--) {

int digit = digits[i] + carry;

if (digit >= 10) {

carry = 1;

digits[i] = digit - 10;

}

else {

digits[i] = digit;

carry = 0;

break;

}

}

if (carry == 1) {

result[0] = 1;

for (int i = 0; i < len; i++) {

result[i + 1] = digits[i];

}

return result;

}

return digits;

}

}