CodeFights Explainer: Trees

data structures trees

Trees. They’re considered to be a computer science basic, but if it’s been a while since you’ve dealt with them – or if you’ve never encountered them before at all – they can be daunting. But tree questions are extremely common in technical interviews, so they’ll come up while you’re finding a job. And then on the job, they’re a wildly useful data structure. So let’s get you up to speed on trees! A tree is a data structure that

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CodeFights Explainer: Prefix Sums

Prefix Sums

Prefix sums, or cumulative sums, allow us to quickly find the sum of any contiguous slice of an array. As a quick example, suppose you copy down some driving directions. They tell you to drive down Penny Lane for 3 miles, then make a left onto Abbey Road, which we travel down for 5 miles before continuing on Lake Shore Drive for 4 miles, and so on. We convert these directions into the number of miles driven on each road.

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