二分查找

 1 public class BinarySearch 
 2 {
 3     
 4     public static int search(int[] array, int n)
 5     {
 6         int low = 0, mid = 0;
 7         int high = array.length - 1;
 8     
 9         while (low <= high) {
10             
11             mid = (low + high) >> 1;
12             
13             if (array[mid] == n) 
14                 return mid;
15             
16             if (array[mid] > n) 
17                 high = mid - 1;
18             else
19                 low = mid + 1;
20         }
21         
22         return -1;
23     }
24     
25     
26     public static void main(String[] args)
27     {
28         int[] array = new int[100];
29         
30         for (int i = 0; i < 100; i++) {
31             array[i] = 100 + i;
32         }
33         
34         int result = BinarySearch.search(array, 198);
35         
36         System.out.println(result);
37     }
38     
39 }