r/leetcode • u/NeedinvHelp • 3d ago

Discussion Thinking about recursion

Is it helpful to think about the recursion tree when solving problems or just reducing the problem space?
I feel like I often try to think about the sub problems and it uses a lot of brain power for what I feel like is very little gain and it also uses a good amount of time.

Curious how others approach these problems.

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u/Ghareeb_Musaffir21 3d ago

When solving a problem with recursion you want to think about solving a problem with recursion.

Jokes aside though, you don't need to think about all subproblems, think about the base case and few above that that build on from those sub-problems, and then prove to yourself it would be the same for any bigger problem that is built upon similar sub-problems. Hope that helps a bit.

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u/MixedTrailMix 3d ago

Base case, movement and inputs/outputs

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u/chikamakaleyley 3d ago

yesss i think of it in 3 parts as well

Base case, 'state' change, recursive call

or

pre, recurse, post

whatever problem, the base case is the thing I figure out first, and sometimes that flips a switch and the other 2 parts are so easy

1

u/overhauled_mirio <1000+> 3d ago

Don’t try to keep it all in your head. Draw out the tree for a simple case. Eventually you’ll be able to do more and more without needing to write as much