Array Problems

Everything about Array Problems

1. Article · Java

   Dominant Pairs — Sorting and Two-Pointer Approach in Java

   Given an even-sized integer array, divide the array into two equal halves. A pair (i, j) is considered a dominant pair if i belongs to the first half, j belongs to the second half, and arr[i] >= 5 × arr[j]. The goal is to count the total number of dominant pairs efficiently. A brute-force approach takes O(n²) time. By sorting both halves independently and using the two-pointer technique, we can solve the problem in O(n log n) time. This problem is a good example of how sorting can optimize pair-counting problems by avoiding unnecessary comparisons.

   Sandhiya PriyaSep 162,0751,000
2. Article · Java

   Maximize Sum of Adjacent Differences with 1 Replacement

   Given an integer array, you can replace any number of elements with 1. The goal is to maximize the sum of absolute differences between consecutive elements. This article explains how to solve the problem efficiently using a two-state Dynamic Programming approach in O(n) time and O(1) auxiliary space. It includes the intuition, DP states, transitions, Java implementation, and a step-by-step dry run.

   Sandhiya Priya
3. Article · Data Structures and Algorithms (DSA)

   Maximum Subarray Sum by Removing At Most One Element (DP)

   Master the Maximum Subarray Sum problem with at most one deletion using dynamic programming. Optimize with O(N) time and O(1) space.

   Sandhiya PriyaJul 11,3981,000