算法：折半查找（二分查找）

public class Main {
	public static int Max = 20;
	public static int data[] = { 12, 16, 19, 22, 25, 32, 39, 39, 48, 55, 57,58,63, 68, 69, 70, 78, 84, 88, 90, 97 };
	public static int count = 1;
	public static void main(String[] args) {
		System.out.println("请输入您要查找的数字：");
		Scanner sc = new Scanner(System.in);
		int KeyValue = sc.nextInt();
		if (Search(KeyValue)) {
			System.out.println("共查找了" + count + "次");
		} else {
			System.out.println("抱歉,数据数组源中找不到您输入的数字");
		}
	}
 
	public static boolean Search(int k) {
		int left = 0;
		int right = Max - 1;
		int middle;
		while (left <= right) {
			middle = (left + right) / 2;
			if (k < data[middle]) {
				right = middle - 1;
			} else if (k > data[middle]) {
				left = middle + 1;
			} else if (k == data[middle]) {
				System.out.println("Data[" + middle + "] = " + data[middle]);
				return true;
			}
			count++;
		}
		return false;
	}
}