Add Binary (Easy)

Description

Given two binary strings, return their sum (also a binary string).
For example,
a = “11”
b = “1”
Return “100”.

Analysis

模拟大数加法

My Solution

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//C++
class Solution {
public:
    string addBinary(string a, string b) {
        reverse(a.begin(),a.end());
        reverse(b.begin(),b.end());
        string ans="";
        int alen = a.length(),blen = b.length();
        int len = max(alen,blen);
        int x,y,num=0;
        for(int i=0;i<len;i++){
            if(i>=alen)
                x = 0;
            else
                x = a[i]-'0';
            if(i>=blen)
                y = 0;
            else
                y = b[i]-'0';
            ans += (x+y+num)%2+'0';
            num = (x+y+num)/2;
        }
        while(num){
            ans+=num%2+'0';
            num/=2;
        }
        reverse(ans.begin(),ans.end());
        return ans;
    }
};