I need help regarding weird time limit exceeded error in cpp

Question

So there was this code which got accepted when i took its output in a vector

#include <iostream>
#include<vector>
using namespace std;
int main(){
    int t; cin >> t;
    while(t--){
        vector<int>v;
        int n,k; cin >> n >> k;
        for(int i=0;i<n;i++){
            int x; cin >> x;
            if(x%k==0) v.push_back(1);
            else v.push_back(0);
        }
        for(auto x:v) cout <<x <<"";
        cout << endl;
    }
    return 0;
}

but then there is this code gives Time Limit Exceeded error when i am direct printing it

#include <bits/stdc++.h> 
using namespace std;
#define ll long long int

int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        ll k,d;
        int n,i;
        cin>>n>>k;
        for(i=0;i<n;i++)
        {
            cin>>d;
            if(d%k==0)
                cout<<"1";
            else
                cout<<"0";
        }
        cout<<"\n";
    }
}

Can you tell why? (The contest is now over) Here is the question in case

Edit:1 I used int instead of long long as well as printf as well as cin.tie(NULL) stuff, but still to no avail

Answer 1

The implementation with the cout in the for loop body is going to bottle-beck on the cout output for sure, especially given a modulo operation is very cheap in contrast.

See below question as reference:

C++: Does cout statement makes code slower

Something like this would work better:

#include <bits/stdc++.h> 
#include <vector>
using namespace std;
#define ll long long int

int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        ll k,d;
        int n,i;
        cin>>n>>k;
        
        std::vector<bool> r(n);
        for(i=0;i<n;i++)
        {
            cin>>d;
            if(d%k==0)
                r[i] = true;
        }
        
        for(auto i : r)
            cout<<(i ? '1' : '0')<<endl;
        
        cout<<"\n";
    }
}