Binary Search

BinarySearch.java

import java.util.Arrays;

public class BinarySearch
{
    private BinarySearch() { }

    public static int indexOf( int[] a, int key )
    {
        int lo = 0;
        int hi = a.length - 1;
        while ( lo <= hi )
        {
            int mid = lo + ( hi - lo ) / 2;
            if      ( key < a[ mid ] ) hi = mid - 1;
            else if ( key > a[ mid ] ) lo = mid + 1;
            else return mid;
        }
        return -1;
    }

    @Deprecated
    public static int rank( int key, int[] a )
    {
        return indexOf( a, key );
    }

    public static void main( String[] args )
    {

        In in = new In( args[0] );
        int[] whitelist = in.readAllInts( );

        Arrays.sort( whitelist );

        while ( !StdIn.isEmpty( ) )
        {
            int key = StdIn.readInt( );
            if ( BinarySearch.indexOf( whitelist, key ) == -1 )
                StdOut.println( key );
        }
    }
}