Took me 6 months to realize I was nesting my loops all wrong and making my code 10x slower

I was working on a small project for my class, sorting through a list of 500 customer names and orders. My program kept timing out and I couldn't figure out why. My buddy glanced at my screen for like 5 seconds and pointed out I had a nested loop inside another loop that was running 250,000 times when it only needed 500. Felt pretty dumb honestly. Has anyone else had that moment where one tiny fix makes everything click?

2 comments

2 Comments

rosew371mo ago

Oh man, that loop realization hits hard doesn't it? I used to think nesting loops was just how you got things done in programming, like putting a for loop inside a while loop was totally normal and efficient. But then I had this project where I was processing user comments and replies, and my code was crawling. Turned out I had three loops deep checking every single user against every single comment against every single reply, which was like a million iterations for 50 users. A senior dev explained a lookup table to me and suddenly my code ran in like 2 seconds flat. Made me completely rethink how I approach any kind of data matching now.

spencer1991mo ago

Yeah that three deep nested loop nightmare is brutal, glad you got it sorted.