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fixed merge sort (#2202)
* reformat merge sort * Formatted with Google Java Formatter Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
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@ -1,22 +1,18 @@
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package Sorts;
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package Sorts;
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import static Sorts.SortUtils.print;
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/**
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/**
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* This method implements the Generic Merge Sort
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* Generic merge sort algorithm.
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*
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*
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* @author Varun Upadhyay (https://github.com/varunu28)
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* @author Podshivalov Nikita (https://github.com/nikitap492)
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* @see SortAlgorithm
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* @see SortAlgorithm
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*/
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*/
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class MergeSort implements SortAlgorithm {
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class MergeSort implements SortAlgorithm {
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/**
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/**
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* This method implements the Generic Merge Sort
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* Generic merge sort algorithm implements.
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*
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*
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* @param unsorted the array which should be sorted
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* @param unsorted the array which should be sorted.
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* @param <T> Comparable class
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* @param <T> Comparable class.
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* @return sorted array
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* @return sorted array.
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*/
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*/
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@Override
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@Override
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public <T extends Comparable<T>> T[] sort(T[] unsorted) {
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public <T extends Comparable<T>> T[] sort(T[] unsorted) {
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@ -25,13 +21,13 @@ class MergeSort implements SortAlgorithm {
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}
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}
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/**
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/**
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* @param arr The array to be sorted
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* @param arr the array to be sorted.
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* @param left The first index of the array
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* @param left the first index of the array.
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* @param right The last index of the array Recursively sorts the array in increasing order
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* @param right the last index of the array.
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*/
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*/
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private static <T extends Comparable<T>> void doSort(T[] arr, int left, int right) {
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private static <T extends Comparable<T>> void doSort(T[] arr, int left, int right) {
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if (left < right) {
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if (left < right) {
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int mid = left + (right - left) / 2;
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int mid = (left + right) >>> 1;
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doSort(arr, left, mid);
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doSort(arr, left, mid);
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doSort(arr, mid + 1, right);
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doSort(arr, mid + 1, right);
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merge(arr, left, mid, right);
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merge(arr, left, mid, right);
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@ -39,15 +35,16 @@ class MergeSort implements SortAlgorithm {
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}
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}
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/**
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/**
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* This method implements the merge step of the merge sort
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* Merges two parts of an array.
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*
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*
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* @param arr The array to be sorted
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* @param arr the array to be merged.
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* @param left The first index of the array
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* @param left the first index of the array.
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* @param mid The middle index of the array
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* @param mid the middle index of the array.
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* @param right The last index of the array merges two parts of an array in increasing order
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* @param right the last index of the array merges two parts of an array in increasing order.
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*/
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*/
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private static <T extends Comparable<T>> void merge(T[] arr, int left, int mid, int right) {
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private static <T extends Comparable<T>> void merge(T[] arr, int left, int mid, int right) {
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int length = right - left + 1;
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int length = right - left + 1;
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@SuppressWarnings("unchecked")
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T[] temp = (T[]) new Comparable[length];
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T[] temp = (T[]) new Comparable[length];
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int i = left;
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int i = left;
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int j = mid + 1;
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int j = mid + 1;
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@ -72,21 +69,20 @@ class MergeSort implements SortAlgorithm {
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System.arraycopy(temp, 0, arr, left, length);
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System.arraycopy(temp, 0, arr, left, length);
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}
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}
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// Driver program
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/** Driver code */
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public static void main(String[] args) {
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public static void main(String[] args) {
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// Integer Input
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Integer[] arr = {4, 23, 6, 78, 1, 54, 231, 9, 12};
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MergeSort mergeSort = new MergeSort();
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MergeSort mergeSort = new MergeSort();
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Integer[] arr = {4, 23, 6, 78, 1, 54, 231, 9, 12};
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mergeSort.sort(arr);
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mergeSort.sort(arr);
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for (int i = 0; i < arr.length - 1; ++i) {
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assert arr[i] <= arr[i + 1];
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}
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// Output => 1 4 6 9 12 23 54 78 231
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print(arr);
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// String Inpu
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String[] stringArray = {"c", "a", "e", "b", "d"};
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String[] stringArray = {"c", "a", "e", "b", "d"};
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mergeSort.sort(stringArray);
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mergeSort.sort(stringArray);
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// Output => a b c d e
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for (int i = 0; i < stringArray.length - 1; ++i) {
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print(stringArray);
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assert arr[i].compareTo(arr[i + 1]) <= 0;
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}
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}
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}
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}
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}
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