Binary Search 总结

binary search模板：
 1 class Solution {
 2     /**
 3      * @param nums: The integer array.
 4      * @param target: Target to find.
 5      * @return: The first position of target. Position starts from 0.
 6      */
 7     public int binarySearch(int[] nums, int target) {
 8         if (nums == null || nums.length == 0) {
 9             return -1;
10         }
11         
12         int start = 0, end = nums.length - 1;
13         while (start + 1 < end) {
14             int mid = start + (end - start) / 2;
15             if (nums[mid] == target) {
16                 end = mid;  
17             } else if (nums[mid] < target) {
18                 start = mid;
19             } else {
20                 end = mid;
21             }
22         }
23         if (nums[start] == target) {
24             return start;
25         }
26         if (nums[end] == target) {
27             return end;
28         }
29         return -1;
30     }
31 }