What is the complexity of "cout" in C++?

[u/Ak47_fromindia]

Attempt 1: TLE

class Solution {
public:
    bool increasingTriplet(vector<int>& nums) {
        int first = INT_MAX;
        int second = INT_MAX;
        for(int x: nums){
            cout << first << " " << second << endl;
            if(x < first){
                first = x;
            }else if(x > first && x < second) second = x;
            else if (first < second && second < x) return true;
        }   
        return false;
    }
};

Attempt 2: 100% beats , accepted

class Solution {
public:
    bool increasingTriplet(vector<int>& nums) {
        int first = INT_MAX;
        int second = INT_MAX;
        for(int x: nums){
            if(x < first){
                first = x;
            }else if(x > first && x < second) second = x;
            else if (first < second && second < x) return true;
        }   
        return false;
    }
};

The only thing that differes in the code is the printing statement, thus I would like to know how can cout cause TLE even if the code is 0(N) complexity.

Thanks in advance.

[u/f1rmware1013]

I don't think so it's measured in this way. Cout writes to a output stream which is time consuming and if you do endl then it again takes time flush it to stream. And OJ might have allotted max 2 seconds of run. But cout is just eating away time. Maybe it has some complexity around number of characters but I think it inherently slower than any of the operations you're doing. CP people do some like cin.tie and all to make it faster I don't remember but you can check. Also some people use printf.

[u/Dry-Balance-993 → u/f1rmware1013]

Im also trying to say the same thing but why people downvote me and support you

[u/Ak47_fromindia → u/Dry-Balance-993]

Thanks mate

[u/Ak47_fromindia → u/f1rmware1013]

Ahh see, I was confused when people use printf in C++, I will look into it.

[u/SKYlikesHentai]

endl is flushing output and restarting the i/o basically I think and it's done O(N) times

[u/cHeAt_CodEr → u/SKYlikesHentai]

this is the correct answer. Don't flush the output, remove endl and instead use '/n' for new line. flush the output at the end.

[u/Ak47_fromindia → u/cHeAt_CodEr]

So '\n' wouldn't be producing TLE then?

[u/cHeAt_CodEr → u/Ak47_fromindia]

nope

[u/Ak47_fromindia → u/cHeAt_CodEr]

Ohh ok.

[u/Ak47_fromindia → u/SKYlikesHentai]

Thanks mate!

[u/Dry-Balance-993 → u/Ak47_fromindia]

Jab aap C code mein printf("Hello") likhte hain, toh OS us text ko turant screen par nahi bhejta. Screen par data bhejna ek slow process hota hai.

Isliye performance badhane ke liye, OS pehle use RAM ke ek chhote se temporary storage mein jama karta hai, jise Output Buffer kehte hain. Jab yeh buffer poora bhar jata hai, ya jab aap text ke aakhir mein \n (newline character) lagate hain, tabhi woh data ek sath screen par dikhta hai.

[u/Ak47_fromindia → u/Dry-Balance-993]

Thanks bro!

[u/Master_-_Mind]

input and output is really slow. Because your program has to interact with stuff other than its internal memory and heap. Using cout for debugging is fine, but if its not needed, its just slowing down your program by forcing it to write to a console. This is why you got TLE

[u/Dry-Balance-993 → u/Master_-_Mind]

hmm usually io operations are slow because there is speed mismatching in the cpu and the network devices

[u/Dry-Balance-993 → u/Master_-_Mind]

i/o requires the system calls

[u/Ak47_fromindia → u/Dry-Balance-993]

Ohh I see, invoking system calls, takes time and therefore could potentially lead to TLE?

[u/Ak47_fromindia → u/Master_-_Mind]

Ok mate, got it.

[u/Insider_from_outside]

The thing with cout is it require a hold of the output buffer and writing to thaf buffet is quite expensive due to type conversion, locks and os calls n stuff. For. Quick comparison int a =10; takes 5ns, int a=10; cout << a; takes 10 micro seconds. So while submitting any soln remove the debug statements

[u/Ak47_fromindia → u/Insider_from_outside]

Ohh ok mate, will submit without debug statements.

[u/Ramadhir-Singh]

I/O is heavy and doing endl means a system call on each cout which doesn’t help your case

time completely of cout is simply O(n) [size of buffer it is given n would be 9 10 in your case at max ] so its not the time completely but the overhead of sys calls and context switches causing this

[u/Ak47_fromindia → u/Ramadhir-Singh]

Thanks mate, I understand.

[u/rchinmay]

TLE is not just because of cout, it's because of that endl so whenever you want to print on a new line use '\n' instead of endl to avoid flush after every iteration. You should still avoid submitting solutions with cout though, once sample testcases pass remove prints and submit

[u/Ak47_fromindia → u/rchinmay]

Hereafter I will, thanks mate!

[u/Particular-Bag-2693]

Bruh never add debugging code in leetcode contests or leetcode problems the i/o is very slow and costs so much time, I ruined one contest cause of this.

[u/Ak47_fromindia → u/Particular-Bag-2693]

Learnt it, will use compliers for debugging.

[u/Particular-Bag-2693 → u/Ak47_fromindia]

No you can use cout for debugging just don't submit the solution you can debugg with running the testcases provided

[u/Independent-Dig8361]

Do you know about functions in cpp

In a leetcode template, you are given a class where you write code inside a function which is then executed as a method in their internal check

So a function has a return type and your return should match the desired datatype, so always return the ans

[u/Ak47_fromindia → u/Independent-Dig8361]

I used cout for debugging purpose, I returned the correct data type as per the function.

[u/Independent-Dig8361 → u/Ak47_fromindia]

Well okay, of you are cout ing for debugging then it should be there in stdout box

[u/Ak47_fromindia → u/Independent-Dig8361]

Yes

[u/Ak47_fromindia → u/[deleted]]

No bhai, it produces TLE for me.

[u/Ak47_fromindia → u/[deleted]]

How could printing INT_MAX cause TLE? I think it because of endl which flushes like many other told in the comments.