[leetcode-66-Plus One]

Given a non-negative integer represented as a non-empty array of digits, plus one to the integer.
You may assume the integer do not contain any leading zero, except the number 0 itself.
The digits are stored such that the most significant digit is at the head of the list.

思路：

类似于普通加法，随时判断进位的情况，最后还要判断最高位也有进位。

vector<int> plusOne(vector<int>& digits)
{
    int carry = 0;
    int temp = 0;
    for(int i = digits.size()-1;i >= 0;i--)
    {
         if(i == digits.size()-1 )      temp = digits[i] + 1 + carry;
         else  temp = digits[i] + carry;
         digits[i] = temp%10;
         if( temp>=10)      carry = 1;
        else  carry = 0;
    }
    if(carry == 1)
        digits.insert(digits.begin(),1);
    return digits;
}