二分查找法
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import java.util.Arrays;

public class BinarySearch {

	//Find the number by changing the hight limit and lower limmit of the array. 
	public static int rank(int key, int[] a, Counter n) {
		
		int lo = 0; 
		int hi = a.length - 1;
		while(lo <= hi)
		{
			int mid = lo + (hi - lo) / 2;
			n.increment();
			if(key < a[mid])
				hi = mid - 1;
			else if(key > a[mid])
				lo = mid + 1;
			else
				return mid;
		}
		return -1;
	}
	public static void main(String[] args) {
		
		//Print the number of the key that the whitelist has not.
		int[] whitelist = {1, 9, 4, 7, 8, 25, 11};
		int[] key = {7, 2, 3, 15};
		Counter n = new Counter("n");
		
		Arrays.sort(whitelist);
		for(int i = 0; i < key.length; i++)
		{
			if(rank(key[i], whitelist, n) == -1)
				System.out.println(key[i]);
		}
		System.out.println("the check times is : " + n.tally());
	}

}