"CodingInterviewGuide"--在数组中找到一个局部最小的位置

 1     public int getLocalMinIndex(int[] arr)
 2     {
 3         if(arr == null || arr.length == 0)
 4         {
 5             return -1;
 6         }
 7         if(arr.length == 1 || arr[0] ])
 8         {
 9             return 0;
10         }
11         if(arr[arr.length - 1] ])
12         {
13             return arr.length - 1;
14         }
15         int left = 1;
16         int right = arr.length - 2;
17         while(left < right)
18         {
19             int mid = (left + right) / 2;
20             if(arr[mid] > arr[mid - 1])
21             {
22                 right = mid - 1;
23             }
24             else if(arr[mid] > arr[mid + 1])
25             {
26                 left = mid + 1;
27             }
28             else
29             {
30                 return mid;
31             }
32         }
33         return left;
34     }