1622 Fancy Sequence

Solution Link: https://leetcode.com/problems/fancy-sequence/solutions/7649389/1622-fancy-sequence-by-477u6uqyfv-w3wk In this video, we solve LeetCode problem 1622, Fancy Sequence. The problem asks us to design a data structure that supports append, addAll, multAll, and getIndex operations efficiently. Since addAll and multAll affect every element in the sequence, a naive solution would be too slow. In this tutorial, we use a clever mathematical approach with modular arithmetic and lazy transformations to perform all operations in constant time. We walk through the full code, explain the intuition behind normalized values, and show how to reconstruct the actual sequence values when needed. The video also covers the step-by-step approach, example walkthrough, and detailed analysis of time and space complexity. This problem is a great example of how mathematical transformations and modular arithmetic can help optimize data structure operations for large input sizes.