[LintCode] Last Position of Target

Find the last position of a target number in a sorted array. Return -1 if target does not exist.

Example

Given [1, 2, 2, 4, 5, 5].

For target = 2, return 2.

For target = 5, return 5.

For target = 6, return -1.

 1 public class Solution {
 2     /*
 3      * @param nums: An integer array sorted in ascending order
 4      * @param target: An integer
 5      * @return: An integer
 6      */
 7     public int lastPosition(int[] nums, int target) {
 8         if(nums == null || nums.length == 0) {
 9             return -1;
10         }
11         int low = 0, high = nums.length - 1;
12         while(low + 1< high) {
13             int mid = low + (high - low) / 2;
14             if(nums[mid] == target) {
15                 low = mid;
16             }
17             else if(nums[mid] > target) {
18                 high = mid - 1;
19             }
20             else {
21                 low = mid + 1;
22             }
23         }
24         if(nums[high] == target) {
25             return high;
26         }
27         else if(nums[low] == target) {
28             return low;
29         }
30         return -1;
31     }
32 }