content: import java.util.Arrays;
  
  /**
   * Implementation of Merge Sort
   *
   * Time Complexity: O(n*log(n))
   * Space Complexity: O(n)
   *
   * Author: AnxietyMedicine (GitHub)
   */
  public class MergeSort {
      // Merges two subarrays of arr[]
      // First subarray is arr[l..m]
      // Second subarray
      public void merge(int[] arr, int l, int m, int r) {
          // Find sizes of two subarrays to be merged
          int n1 = m - l + 1;
          int n2 = r - m;
  
          /* Create temp arrays */
          int[] L = new int[n1];
          int[] R = new int[n2];
  
          /* Copy data to temp arrays */
          for (int i = 0; i < n1; i++)
              L[i] = arr[l + i];
          for (int j = 0; j < n2; j++)
              R[j] = arr[m + 1 + j];
  
          /* Merge the temp arrays */
  
          // Initial indexes of first and second subarrays
          int i = 0, j = 0;
  
          // Initial index of merged subarray array
          int k = l;
          while (i < n1 && j < n2) {
              if (L[i] <= R[j]) {
                  arr[k] = L[i];
                  i++;
              } else {
                  arr[k] = R[j];
                  j++;
              }
              k++;
          }
  
          /* Copy remaining elements of L[] if any */
          while (i < n1) {
              arr[k] = L[i];
              i++;
              k++;
          }
  
          /* Copy remaining elements of R[] if any */
          while (j < n2) {
              arr[k] = R[j];
              j++;
              k++;
          }
      }
  
      // Main function that sorts arr[l..r] using merge()
      public void sort(int[] arr, int l, int r) {
          if (l < r) {
              // Find the middle point
              int m = (l + r) / 2;
  
              // Sort first and second halves
              sort(arr, l, m);
              sort(arr, m + 1, r);
  
              // Merge the sorted halves
              merge(arr, l, m, r);
          }
      }
  
      public static void main(String[] args) {
          int[] arr = {12, 11, 13, 5, 6, 7};
  
          System.out.println("Given array: " + Arrays.toString(arr));
  
          MergeSort ms = new MergeSort();
          ms.sort(arr, 0, arr.length - 1);
  
          System.out.println("\nSorted array: " + Arrays.toString(arr));
      }
  }
  