### Prefix Sum: Trading Space for Time

This problem can be solved with a Prefix Sum approach. Basically we can calculate and store the partial array sum from 0..i, for each i. That way we can easily compute the average needed (just use long for the prefix sum array since the addition may go past Max.Int). This way we're trading space (O(n)) for time (also O(n)). Code is down below, cheers, ACC. K Radius Subarray Averages - LeetCode 2090. K Radius Subarray Averages Medium 111 1 Add to List Share You are given a 0-indexed array nums of n integers, and an integer k . The k-radius average for a subarray of nums centered at some index i with the radius k is the average of all elements in nums between the indices i - k and i + k ( inclusive ). If there are less than k elements before or after the index i , then the k-radius average is -1 . Build and return an array avgs of length n where avgs[i] is the k-radius average for the subarray centered at index i . The average of x ele