import java.util.Arrays;
class Main {
public static void main(String[] args) {
int[] array = new int[]{1,2,3,4,5};
Arrays.sort(array);
// System.out.println("Hello World!:" + findFirstIndexOf(12, array));
System.out.println(Arrays.toString(array));
System.out.println("Hello World!:" + binarySearch(100, array));
}
public static int binarySearch(int el, int[] arr) {
return binarySearchRecursive(el, arr, 0, arr.length);
}
private static int binarySearchRecursive(int el, int[] arr, int start, int end) {
if (arr == null || arr.length == 0 || start >= end-1) return -1;
int mid = (start == 0) ? (end-start)/2 : (end-start)/2 + start;
if (arr[mid] == el) return mid;
else if (el < arr[mid]) {
return binarySearchRecursive(el, arr, start, mid);
}
else {
return binarySearchRecursive(el, arr, mid, end);
}
}
}
