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

Console I/O is expensive. You should avoid putting it into busy loops if possible. I think that could be a huge performance hit. You're best off getting all input, processing, then printing all output in most cases since I/O in this case is probably your bottle-neck. — Jeremy, Jul 25 '20 at 18:24
Probably irrelevant, but there are other difference in the code: you are using `long long` in the 2nd, and printing strings instead of ints. When comparing 2 pieces of code, try and remove all differences except what you're trying to compare. — cigien, Jul 25 '20 at 18:28
... and this is just the nth example of why if someone's goal is to learn C++, they won't learn anything from these worthless contests. In nearly all cases, like this one, the correct solution is requires knowledge of a particular programming trick. If you don't know what the trick is and attempt to code a brute-force approach, the program runs slow and fails for that reason. If you're trying to learn C++, you won't learn anything from meaningless online contest sites [but only from a good C++ textbook](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list). — Sam Varshavchik, Jul 25 '20 at 18:32
@SamVarshavchik -- Unfortunately it seems that a lot of newbies are being absorbed into solving these questions because they have been told that they will get a lucrative job at a major software company if they can solve these questions and get some sort of "high rank" to show some recruiter.. That's the retort I seem to get when I ask them "what good are these tests?" That's probably also the reason why you see a lot of cries of desperation, and sometimes no effort in these questions -- gotta get those ranking points on the question site. — PaulMcKenzie, Jul 25 '20 at 18:52
I don't know if it will provide a lucrative job or not but it definitely is a good practice ground for Google Code Jam or Kickstart or FB Hacker's cup — Abhijeet Srivastava, Jul 26 '20 at 05:43

Jeremy · Answer 1 · 2020-07-25T20:42:40.820

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";
    }
}

I need help regarding weird time limit exceeded error in cpp

1 Answers1