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vinhhocptit's blog

Does scanf compared to cin really affects complexity that much ?
By vinhhocptit, history, 5 hours ago, In English

Today, I had spent hours trying to solve problem : (https://codeforces.me/contest/1334/problem/C) and submitted several solutions with an O(n) complexity, but I kept getting a TLE. After some further inspection, I changed from using cin to scanf, and my solution was finally accepted. While it's well-known that scanf is slightly faster than cin, I was surprised by how much of a difference it actually made in this case.

TLE Code : 284211972 Accepted Code : 284212724

This blog may not be overly educational, but I just want to highlight that even a O(n) solution can lead to a TLE error. Understanding this can help you avoid the frustration and wasted time that I experienced.

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5 hours ago, # |
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ios::sync_with_stdio(false);cin.tie(nullptr); cout.tie(nullptr);

Use this if you want to use cin/cout

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    5 hours ago, # ^ |
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    what does cout.tie(nullptr) do?

    explanation

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      5 hours ago, # ^ |
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      cout = Output + cout.flush(). But if you use cout.tie(nullptr) it will untie the cin with cout. So cout = Output only. In interective problems if you don't use cout.tie(nullptr); you don't have to use flush manually as it will be done automatically.

      Using this will help a lot with time complexity specially when you have multiple test cases.

      And forgive my poor English

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        114 minutes ago, # ^ |
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        no, it's all about cin.tie(nullptr); as far as i know

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5 hours ago, # |
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I thought everyone learns to put cin.tie(0) -> sync_with_stdio(0) in their code the first day they start cp.

Guess not :/

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    5 hours ago, # ^ |
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    I know thats a fundamental thing in CP but I never thought that it would matters that much but I guess im wrong lol.

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