Prefix Sum

Definition

An array `P` where `P[i]` is the sum of all elements from index `0` to `i`. It allows calculating the sum of any subarray `[L, R]` in O(1) time using the formula `P[R] - P[L-1]`.

Explain Like I'm New

Pre-calculating a running total so that if someone asks 'what is the sum from day 5 to day 10', you just take 'Total at day 10' minus 'Total at day 4'.

Interactive Coding Challenges

Calculate Prefix Sum Array

Solution Code

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