Merging.java

public class Merging{
 public static void mergeSort(int[] arr, int left, int right) {
        if (left < right) {
            // Find the middle point
            int mid = (left + right) / 2;

            // Recursively sort first and second halves
            mergeSort(arr, left, mid);
            mergeSort(arr, mid + 1, right);

            // Merge the sorted halves
            merge(arr, left, mid, right);
        }
    }

    // Merge two sorted subarrays arr[left..mid] and arr[mid+1..right]
    public static void merge(int[] arr, int left, int mid, int right) {
        // Sizes of two subarrays
        int n1 = mid - left + 1;
        int n2 = right - mid;

        // Temporary 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[left + i];
        for (int j = 0; j < n2; j++)
            R[j] = arr[mid + 1 + j];

        // Merge temp arrays back into arr[]
        int i = 0, j = 0, k = left;

        while (i < n1 && j < n2) {
            if (L[i] <= R[j]) {
                arr[k++] = L[i++];
            } else {
                arr[k++] = R[j++];
            }
        }

        // Copy remaining elements of L[]
        while (i < n1) {
            arr[k++] = L[i++];
        }

        // Copy remaining elements of R[]
        while (j < n2) {
            arr[k++] = R[j++];
        }
    }

    // Utility function to print the array
    public static void printArray(int[] arr) {
        for (int num : arr)
            System.out.print(num + " ");
        System.out.println();
    }
    public static void main(String[] args) {
          int[] arr = { 38, 27, 43, 3, 9, 82, 10 };
        System.out.println("Original array:");
        printArray(arr);

        mergeSort(arr, 0, arr.length - 1);

        System.out.println("Sorted array:");
        printArray(arr);
    }
}