Sieve of Eratosthenes to solve a Leetcode problem III

In this case the Sieve is applied directly to the main loop. Notice that you don't need to save off the elements in different arrays, only add them up. Also important to note that composite numbers can be created in multiple ways (for example, 2*6 == 3*4), hence keep track of which ones you have seen before to avoid double counting. No GAI involved, except at the very bottom to compute the Big-O time complexity, which I think it would have been of the order of NLogN, but the true analysis from OpenAI O3 (Advanced Reasoning) is down below. So is the code. Cheers, ACC. Split Array by Prime Indices - LeetCode You are given an integer array nums . Split nums into two arrays A and B using the following rule: Elements at prime indices in nums must go into array A . All other elements must go into array B . Return the absolute difference between the sums of the two arrays: |sum(A) - sum(B)| . Note: ...