6_3_addition_of_binary_numbers_function.cpp

#include<iostream>
using namespace std;

// This code will not work for numbers like 1+1, 10101+11011, etc.

int reverse(int n)
{
    int ans=0;
    while(n>0)
    {
        int lastDigit=n%10;
        ans=ans*10+lastDigit;
        n/=10;
    }
    return ans;
}


int addBinary(int a,int b)
{
    int ans=0;
    int prevCarry=0;

    while(a>0 && b>0)
    {
        if(a%2==0 && b%2==0)
        {
            ans=ans*10+prevCarry;
            prevCarry=0;
        }
        else if((a%2==0 && b%2==1) || (a%2==1 && b%2==0))
        {
            if(prevCarry==1)
            {
                ans=ans*10+0;
                prevCarry=1;
            }
            else
            {
                ans=ans*10+1;
                prevCarry=0;
            }
        }
        else
        {
            ans=ans*10+prevCarry;
            prevCarry=1;
        }
        a/=10;
        b/=10;
    }

    while(a>0)
    {
        if(prevCarry==1)
        {
            if(a%2==1)
            {
                ans=ans*10+0;
                prevCarry=1;
            }
            else
            {
                ans=ans*10+1;
                prevCarry=0;
            }
        }
        else
        {
            ans=ans*10+(a%2);
        }
        a/=10;
    }

    while(b>0)
    {
        if(prevCarry==1)
        {
            if(b%2==1)
            {
                ans=ans*10+0;
                prevCarry=1;
            }
            else
            {
                ans=ans*10+1;
                prevCarry=0;
            }
        }
        else
        {
            ans=ans*10+(b%2);
        }
        b/=10;
    }


    if(prevCarry==1)
    {
        ans=ans*10+1;
    }

    ans=reverse(ans);
    return ans;
}


int main(){
    int a,b;
    cin>>a>>b;

    cout<<addBinary(a,b);

    return 0;
}