Here’s the question link on LeetCode 42. Trapping Rain Water: https://leetcode.com/problems/trapping-rain-water/description Brute Force O(n²)Better O(n)Another Approach: Monotonic Stack O(n)Optimal O(n) Brute Force O(n²) For every index, I need to figure…
Here’s the question link on LeetCode 189. Rotate Array: https://leetcode.com/problems/rotate-array/description Brute Force O(n × k)Better O(n)Optimal O(n) and O(1) SpaceCode lines explained Brute Force O(n × k) The simplest way…
Here’s the question link on LeetCode 54. Spiral Matrix: https://leetcode.com/problems/spiral-matrix/description Brute Force [Space - O(m × n)]Optimal [Space - O(1)] Brute Force [Space - O(m × n)] My first thought…
Here’s the question link on LeetCode 74. Search a 2D Matrix: https://leetcode.com/problems/search-a-2d-matrix/description Brute O(n*m)Optimal O(log(n*m))Code Lines Explained Brute O(n*m) A brute-force way is to perform an n*m search every time:…
Here's the question link on LeetCode 53. Maximum Subarray: https://leetcode.com/problems/maximum-subarray/description Brute O(n^2)Optimal - O(n)Why can we not use prefix sums?Why does Kadane's work? Brute O(n^2) Try all possible subarrays using…