Abito's blog

Use proper upper_bound()
By Abito, history, 2 years ago, In English

Many people use the normal upper_bound() function, which is slow (at worst case O(n)) and get TLE. When you are using a set/multiset/map, use containername.upper_bound() This function uses Binary Search which runs at O(logn) time. Please be careful next time. This is only a reminder because I'm seeing a lot of people get TLE because of this.

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2 years ago, # |
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Yeah I got a TLE bc of this today

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    2 years ago, # ^ |
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    RIP. I guess you'll be more careful now

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2 years ago, # |
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Wait, upper_bound() exists? I only learnt the latter form. What is the first function useful for?

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    2 years ago, # ^ |
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    upper bound on literally any sorted thing other than set/map/multiset/multimap/linked list (does technically work on BBSTs/linked lists but they don't have random access iterators so distance() is $$$O(n)$$$ in that case)

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      2 years ago, # ^ |
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      Yeah, but because it is slow you can do Binary Search on your own

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23 months ago, # |
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How to convert a discussion on the SOI group to contribution!

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    23 months ago, # ^ |
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    I guess. Also a lot of people in comments were getting TLEs so yeah

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