java 二分法查找

1package com.test;
2
3import java.util.Arrays;
4
5public class BinaraySearch {
6    
7    public static int search(int key, int[] a) {
8        int lo = 0;
9        int hi = a.length - 1;
10        while (lo <= hi) {
11            int mid = lo + (hi - lo) / 2;
12            
13            if (key < a[mid]) {
14                hi = mid - 1;
15            } else if (key > a[mid]) {
16                lo = mid + 1;
17            } else {
18                return mid;
19            }
20        }
21        return -1;
22    }
23    
24    public static void main(String[] args) {
25        int[] a = new int[] {2,3,19,29,40,11,12,14};
26        // 数组必须是有序的
27        Arrays.sort(a);
28        System.out.println(search(14, a));
29    }
30        
31}