Merge pull request kishanrajput23#187 from shanvijha30/algorithm_shanvi

Merge Sort Algorithm

Author: kishanrajput23

Merge_Sort.java

@@ -0,0 +1,66 @@
+import java.util.*;
+
+class Solution {
+ private static void merge(int[] arr, int low, int mid, int high) {
+ ArrayList<Integer> temp = new ArrayList<>(); // temporary array
+ int left = low; // starting index of left half of arr
+ int right = mid + 1; // starting index of right half of arr
+
+ //storing elements in the temporary array in a sorted manner//
+
+ while (left <= mid && right <= high) {
+ if (arr[left] <= arr[right]) {
+ temp.add(arr[left]);
+ left++;
+ } else {
+ temp.add(arr[right]);
+ right++;
+ }
+ }
+
+ // if elements on the left half are still left //
+
+ while (left <= mid) {
+ temp.add(arr[left]);
+ left++;
+ }
+
+ // if elements on the right half are still left //
+ while (right <= high) {
+ temp.add(arr[right]);
+ right++;
+ }
+
+ // transfering all elements from temporary to arr //
+ for (int i = low; i <= high; i++) {
+ arr[i] = temp.get(i - low);
+ }
+ }
+
+ public static void mergeSort(int[] arr, int low, int high) {
+ if (low >= high) return;
+ int mid = (low + high) / 2 ;
+ mergeSort(arr, low, mid); // left half
+ mergeSort(arr, mid + 1, high); // right half
+ merge(arr, low, mid, high); // merging sorted halves
+ }
+}
+public class tUf {
+ public static void main(String args[]) {
+ Scanner sc = new Scanner(System.in);
+ int n = 7;
+ int arr[] = { 9, 4, 7, 6, 3, 1, 5 };
+ System.out.println("Before sorting array: ");
+ for (int i = 0; i < n; i++) {
+ System.out.print(arr[i] + " ");
+ }
+ System.out.println();
+ Solution.mergeSort(arr, 0, n - 1);
+ System.out.println("After sorting array: ");
+ for (int i = 0; i < n; i++) {
+ System.out.print(arr[i] + " ");
+ }
+ System.out.println();
+ }
+
+}