/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
int *plusOne(int *digits, int digitsSize, int *returnSize)
{
    for (int i = digitsSize - 1; i >= 0; i--)
    {
        if (digits[i] < 9)
        {
            digits[i]++;
            *returnSize = digitsSize;
            return digits;
        }
        else
        {
            digits[i] = 0;
        }
    }

    int *newdigit = (int *)malloc((digitsSize + 1) * sizeof(int));
    newdigit[0] = 1;
    for (int i = 1; i < (digitsSize + 1); i++)
    {
        newdigit[i] = digits[i - 1];
    }
    *returnSize = digitsSize + 1;
    return newdigit;
}