merge

package JAVA.Day17;

public class Divconquar {
    public static void printArr(int arr[]) {
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }

    public static void mergesort(int arr[], int si, int ei) {
        if (si < ei) {
            int mid = (si + ei) / 2;
            mergesort(arr, si, mid); // left part
            mergesort(arr, mid + 1, ei); // right part
            merge(arr, si, mid, ei);
        }
    }

    public static void merge(int[] arr, int si, int mid, int ei) {
        int temp[] = new int[ei - si + 1];
        int i = si;
        int j = mid + 1;
        int k = 0;

        while (i <= mid && j <= ei) {
            if (arr[i] < arr[j]) {
                temp[k++] = arr[i++];
            } else {
                temp[k++] = arr[j++];
            }
        }
        while (i <= mid) {
            temp[k++] = arr[i++];
        }
        while (j <= ei) {
            temp[k++] = arr[j++];
        }
        for (k = 0, i = si; k < temp.length; k++, i++) {
            arr[i] = temp[k];
        }

    }

    public static void main(String[] args) {
        int arr[] = { 5, 6, 4, 2, 3, -1 };
        mergesort(arr, 0, arr.length - 1);
        printArr(arr);
    }
}