Plus One

• Given a non-negative number represented as an array of digits, plus one to the number.

• The digits are stored such that the most significant digit is at the head of the list.

  ---

水题一道，看题目可能不是很明白，可以调试一下看看输出，当vector的首元素也即是number的最高位需要进位时，这时候vector就需要resize以下了。注意到这个情况下面就是敲代码了:).C++代码如下:

class Solution {public:    vector<int> plusOne(vector<int> &digits) {    bool addHead = false;    int i = (digits.size() - 1);    digits[i] += 1;    while( digits[i]>= 10)    {        if(i>0)        {            digits[i] = 0;            digits[i-1] += 1;        }        else        {            digits[i] = 0;            addHead = true;        }        i--;    }    if(addHead)    {        digits.resize(digits.size() + 1);        for(int i =digits.size(); i >0 ; i--)        {            digits[i] = digits[i-1];        }        digits[0] = 1;    }    return digits;    }};