67. Add Binary

程式碼

class Solution {
public:
    string addBinary(string a, string b) {
        if(a.size() < b.size()) // a must longer than b
            swap(a, b);
        for(int i=0; i<b.size(); i++)
        {
            a[a.size() - 1 - i] += b[b.size() - 1 - i] - '0';
        }
        for(int i=a.size() - 1; i>0; i--)
        {
            if(a[i] >= '2')
            {
                a[i-1]++;
                a[i] -= 2;
            }
        }
        if(a[0] >= '2')
        {
            a[0] -= 2;
            a = "1" + a;
        }
        return a;
    }
};