👀 Views: 0 💬 Answers: 1 📅 Created: 2025-06-14

algorithm sorting quicksort Java

I'm wondering if anyone has experience with I'm confused about I'm upgrading from an older version and I'm working on a personal project and Hey everyone, I'm running into an issue that's driving me crazy. I'm stuck on something that should probably be simple. I'm currently implementing the QuickSort algorithm in Java, but I've encountered unstable behavior when dealing with arrays that contain many duplicate elements. My implementation is based on the classic Lomuto partition scheme, but when I sort an array like `{5, 2, 5, 3, 5, 4}`, the order of the duplicate `5`s is not preserved, leading to unexpected results after sorting. Here’s my QuickSort implementation: ```java public class QuickSort { public static void quickSort(int[] arr, int low, int high) { if (low < high) { int pivotIndex = partition(arr, low, high); quickSort(arr, low, pivotIndex - 1); quickSort(arr, pivotIndex + 1, high); } } private static int partition(int[] arr, int low, int high) { int pivot = arr[high]; int i = (low - 1); for (int j = low; j < high; j++) { if (arr[j] <= pivot) { i++; swap(arr, i, j); } } swap(arr, i + 1, high); return i + 1; } private static void swap(int[] arr, int i, int j) { int temp = arr[i]; arr[i] = arr[j]; arr[j] = temp; } } ``` I noticed that while the algorithm sorts correctly in terms of value, the relative order of the duplicate elements changes. I’ve tried altering the pivot selection strategy and even using a stable partitioning method, but nothing seems to help. I'm looking for guidance on how to implement a version of QuickSort that maintains the stability of sorting especially when duplicate values are present. Is it even possible to make QuickSort stable without completely changing the algorithm's nature? Any tips or examples would be greatly appreciated! Any ideas what could be causing this? I'm working on a web app that needs to handle this. How would you solve this? I've been using Java for about a year now. Any ideas how to fix this? This issue appeared after updating to Java stable. How would you solve this? Has anyone else encountered this?