lintcode458- Last Position of Target- easy

public class Solution {
    /*
     * @param nums: An integer array sorted in ascending order
     * @param target: An integer
     * @return: An integer
     */
    public int lastPosition(int[] nums, int target) {
        // write your code here
        if(nums == null || nums.length == 0){
            return -1;
        }
        
        int start = 0;
        int end = nums.length - 1;
        while (start + 1 < end){
            int mid = start + (end - start) / 2;
            if (nums[mid] < target){
                start = mid;
            }
            else if (nums[mid] == target){
                start = mid;
            }
            else {
                end = mid;
            }
        }
        
        if (nums[end] == target){
            return end;
        }
        
        if(nums[start] == target){
            return start;
        }
        
        return -1;
    }
}