【算法】二分法查找

 1 public class Main {
 2     public static void main(String[] args) {
 3         int[] array = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12};
 4         ArrayList<Integer> arrayList = new ArrayList<>();
 5         Arrays.sort(array);
 6 
 7         int target = 11;
 8 
 9         int beginLoc = 0;
10         int endLoc = array.length - 1;
11 
12         while (endLoc > beginLoc) {
13             System.out.println(" beginLoc:" + beginLoc + "endLoc:" + endLoc);
14             if (array[(beginLoc + endLoc + 1) / 2] == target) {
15                 System.out.println("ok");
16                 break;
17             } else if (array[(beginLoc + endLoc + 1) / 2] > target) {
18                 endLoc = (beginLoc + endLoc + 1) / 2;
19             } else {
20                 beginLoc = (beginLoc + endLoc + 1) / 2;
21             }
22         }
23     }
24 }
一定要注意，前后应该分别+1