add_binary_nums.cpp

#include<bits/stdc++.h>
using namespace std;

int reverse(int num)
{
    int ans = 0;
    while(num>0)
    {
        int rem = num % 10;
        ans = ans*10 + rem;
        num /= 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)<<endl;
}