Exercise_1.java

class BinarySearch {

    // Returns index of x if it is present in arr[l.. r], else return -1
    int binarySearch(int arr[], int l, int r, int x) {

        if (r >= l) {

            int mid = l + (r - l) / 2;

            if (arr[mid] == x) {
                return mid;
            }

            if (arr[mid] > x) {
                return binarySearch(arr, l, mid - 1, x);
            }

            return binarySearch(arr, mid + 1, r, x);
        }

        return -1;
    }
}

class Main {

    // Driver method to test above
    public static void main(String args[]) {
        BinarySearch ob = new BinarySearch();
        int arr[] = { 2, 3, 4, 10, 40 };
        int n = arr.length;
        int x = 10;
        int result = ob.binarySearch(arr, 0, n - 1, x);
        if (result == -1)
            System.out.println("Element not present");
        else
            System.out.println("Element found at index " + result);
    }
}