👀 Views: 299 💬 Answers: 1 📅 Created: 2025-06-06

algorithms sorting merge-sort Java

I'm learning this framework and I'm sure I'm missing something obvious here, but I'm having trouble with my implementation of the merge sort algorithm in Java. While it works fine for most inputs, I'm working with unexpected behavior with edge cases, particularly for arrays with duplicate values. The sorting seems inconsistent when the input array contains repeated elements. Here's my implementation: ```java public class MergeSort { public static void mergeSort(int[] arr) { if (arr.length < 2) return; int mid = arr.length / 2; int[] left = Arrays.copyOfRange(arr, 0, mid); int[] right = Arrays.copyOfRange(arr, mid, arr.length); mergeSort(left); mergeSort(right); merge(arr, left, right); } private static void merge(int[] arr, int[] left, int[] right) { int i = 0, j = 0, k = 0; while (i < left.length && j < right.length) { if (left[i] <= right[j]) { arr[k++] = left[i++]; } else { arr[k++] = right[j++]; } } while (i < left.length) { arr[k++] = left[i++]; } while (j < right.length) { arr[k++] = right[j++]; } } } ``` When I run this code with the input `{4, 2, 3, 4, 1, 4}`, the output is `{1, 2, 3, 4, 4, 4}`, which is expected, but for an array like `{1, 1, 1, 2, 2, 2}`, I get `{1, 1, 1, 2, 2, 2}` which is also correct. However, when I test an array with some negative values like `{-1, -1, 0, 1}`, the output is `{-1, -1, 1, 0}` which is incorrect. I’ve debugged the merge function quite a bit but haven’t found anything obviously wrong. The version of Java I'm using is OpenJDK 11. Can anyone guide to identify why the sort is failing in this case and how I can ensure consistent output across all input arrays? I'm working on a application that needs to handle this. Thanks in advance! The project is a web app built with Java.