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.

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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;
    }
};