merge sort code

algorithms/MergeSort.java

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+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class MergeSort {
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        // Input size of the array
+        System.out.print("Enter the number of elements: ");
+        int n = sc.nextInt();
+
+        // Input the array elements
+        int[] arr = new int[n];
+        System.out.println("Enter the elements:");
+        for (int i = 0; i < n; i++) {
+            arr[i] = sc.nextInt();
+        }
+
+        // Create an instance of Solution (assuming Solution is the class name)
+        MergeSort solution = new MergeSort();
+
+        // Call mergeSort to sort the array
+        solution.mergeSort(arr, 0, n - 1);
+
+        // Output the sorted array
+        System.out.println("Sorted array:");
+        System.out.println(Arrays.toString(arr));
+
+        sc.close();
+    }
+
+    /**
+     * Merge two subarrays of arr[]. First subarray is arr[l..m], second subarray is
+     * arr[m+1..r]
+     * 
+     * @param arr The array to be sorted
+     * @param l   Left index of the subarray
+     * @param m   Middle index of the subarray
+     * @param r   Right index of the subarray
+     */
+    void merge(int arr[], int l, int m, int r) {
+        ArrayList<Integer> temp = new ArrayList<>();
+
+        int left = l, right = m + 1;
+
+        while (left <= m && right <= r) {
+            if (arr[left] <= arr[right]) {
+                temp.add(arr[left]);
+                left++;
+            } else {
+                temp.add(arr[right]);
+                right++;
+            }
+        }
+
+        while (left <= m) {
+            temp.add(arr[left]);
+            left++;
+        }
+
+        while (right <= r) {
+            temp.add(arr[right]);
+            right++;
+        }
+
+        for (int i = l; i <= r; i++) {
+            arr[i] = temp.get(i - l);
+        }
+    }
+
+    /**
+     * Main function that sorts arr[l..r] using merge()
+     * 
+     * @param arr The array to be sorted
+     * @param l   Left index of the subarray
+     * @param r   Right index of the subarray
+     */
+    void mergeSort(int arr[], int l, int r) {
+        if (l < r) {
+            int mid = (l + r) / 2;
+
+            // Sort first and second halves
+            mergeSort(arr, l, mid);
+            mergeSort(arr, mid + 1, r);
+
+            // Merge the sorted halves
+            merge(arr, l, mid, r);
+        }
+    }
+}