458. last position of target

public class  {
    public int lastPosition(int[] nums, int target) {
        
        if (nums == null || nums.length == 0) {
            return -1;
        }
        int start = 0, end = nums.length - 1;
        while (start + 1 < end) {
            int mid = start + (end - start) / 2; // avoid out of range
            if (nums[mid] == target) { // answer on the right part
                start = mid;
            } else if (nums[mid] < target) { // answer on the right part
                start = mid;// mid + 1
            } else {
                end = mid; // mid - 1
            }
        }
        if (nums[end] == target) {
            return end;
        } else if (nums[start] == target) {
            return start;
        } else {
            return -1;
        }


    }
}