Leetcode 67. Add Binary 66. Plus One

非常简单，只需要有个进位标记就可以了

// Author : yqtao
// Date   : 2016.6.18
// Email  : [email protected]
/********************************************************************************** 
* * Given two binary strings, return their sum (also a binary string).
* * For example,
* a = "11"
* b = "1"
* Return "100".
* * **********************************************************************************/
#include <iostream>
#include <string>
#include <vector>
using namespace std;
string addBinary(string a, string b)
{
 int alen = a.size(), blen = b.size();
 string result;
 //bool carry = false;//表示是否有进位
 int carry = 0;
 while (alen>0||blen>0)
 {
 int abit = alen <= 0 ? 0 : a[alen - 1] - '0';//转成数字
 int bbit = blen <= 0 ? 0 : b[blen - 1] - '0';
 //int cbit = carry ? 1 : 0;//进位数0 或1
 result.insert(result.begin(), '0' + ((abit + bbit + carry) %2));
 carry = ((abit + bbit + carry) / 2);//大于1说明有进位，则carry=true
 alen--;
 blen--;
 }
 if (carry==1)
 result.insert(result.begin(), '1');//如果最后有进位
 return result;
}

int main()
{
 string a = "11";
 string b = "1";
 cout << addBinary(a, b) << endl;
 return 0;
}

/************************************************************************
*
* 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.
*
************************************************************************/
简单，如上述基本相同

class Solution {
public:
    vector<int> plusOne(vector<int>& digits) {
        int carry=1;
        int len=digits.size();
        vector<int>result(len);
        while (len>0)
        {
            int sum=carry+digits[len-1];
            result[len-1]=sum%10;
            carry=sum/10;
            len--;
        }
        if (carry>0)
            result.insert(result.begin(),1);
         return result;
    }

};