diff --git a/Sorts/MergeSort.java b/Sorts/MergeSort.java index dfd350afb283..57892bc6bc46 100644 --- a/Sorts/MergeSort.java +++ b/Sorts/MergeSort.java @@ -1,22 +1,18 @@ package Sorts; -import static Sorts.SortUtils.print; - /** - * This method implements the Generic Merge Sort + * Generic merge sort algorithm. * - * @author Varun Upadhyay (https://github.com/varunu28) - * @author Podshivalov Nikita (https://github.com/nikitap492) * @see SortAlgorithm */ class MergeSort implements SortAlgorithm { /** - * This method implements the Generic Merge Sort + * Generic merge sort algorithm implements. * - * @param unsorted the array which should be sorted - * @param Comparable class - * @return sorted array + * @param unsorted the array which should be sorted. + * @param Comparable class. + * @return sorted array. */ @Override public > T[] sort(T[] unsorted) { @@ -25,13 +21,13 @@ public > T[] sort(T[] unsorted) { } /** - * @param arr The array to be sorted - * @param left The first index of the array - * @param right The last index of the array Recursively sorts the array in increasing order + * @param arr the array to be sorted. + * @param left the first index of the array. + * @param right the last index of the array. */ private static > void doSort(T[] arr, int left, int right) { if (left < right) { - int mid = left + (right - left) / 2; + int mid = (left + right) >>> 1; doSort(arr, left, mid); doSort(arr, mid + 1, right); merge(arr, left, mid, right); @@ -39,15 +35,16 @@ private static > void doSort(T[] arr, int left, int righ } /** - * This method implements the merge step of the merge sort + * Merges two parts of an array. * - * @param arr The array to be sorted - * @param left The first index of the array - * @param mid The middle index of the array - * @param right The last index of the array merges two parts of an array in increasing order + * @param arr the array to be merged. + * @param left the first index of the array. + * @param mid the middle index of the array. + * @param right the last index of the array merges two parts of an array in increasing order. */ private static > void merge(T[] arr, int left, int mid, int right) { int length = right - left + 1; + @SuppressWarnings("unchecked") T[] temp = (T[]) new Comparable[length]; int i = left; int j = mid + 1; @@ -72,21 +69,20 @@ private static > void merge(T[] arr, int left, int mid, System.arraycopy(temp, 0, arr, left, length); } - // Driver program + /** Driver code */ public static void main(String[] args) { + MergeSort mergeSort = new MergeSort(); - // Integer Input Integer[] arr = {4, 23, 6, 78, 1, 54, 231, 9, 12}; - MergeSort mergeSort = new MergeSort(); mergeSort.sort(arr); + for (int i = 0; i < arr.length - 1; ++i) { + assert arr[i] <= arr[i + 1]; + } - // Output => 1 4 6 9 12 23 54 78 231 - print(arr); - - // String Inpu String[] stringArray = {"c", "a", "e", "b", "d"}; mergeSort.sort(stringArray); - // Output => a b c d e - print(stringArray); + for (int i = 0; i < stringArray.length - 1; ++i) { + assert arr[i].compareTo(arr[i + 1]) <= 0; + } } }