Recursively search for a given element in an array using binary search. The element to find is passed as the last argument and the array is the preceding series of arguments from command prompt!

RecursiveBinarySearch.java

import java.util.Arrays;

class RecursiveBinarySearch{
	static int elem;
	static int passNumber=1;
	public static void main(String ... args){
		elem=Integer.parseInt(args[args.length-1]);
		int [] array;
		if(args.length!=0){
			array= new int [args.length-1];
			
			for(int i=0; i<args.length-1; i++){
				array[i]=Integer.parseInt(args[i]);
			}
			Arrays.sort(array);
			System.out.println(binarySearch(array, 0, array.length-1));
		}

	}

	public static int binarySearch(int [] array, int first, int last){
		System.out.print("Pass "+(passNumber++)+": ");
		for(int i= first; i<=last; i++){
			System.out.print(array[i]+" ");
		}
		System.out.println();
		int middle= (first+last)/2;
		if(elem>array[middle]){
			//check right part of array
			return binarySearch(array, middle+1, last);
		}else if(elem<array[middle]){
			//check left part of array
			return binarySearch(array, first, middle-1);
		}else if(elem == array[middle]){
			//elem is middle element
			return middle;
		}
		return -1;
	}

}