public static int removeDuplicates(int[] nums) {
        if (nums == null || nums.length == 0) {
            return 0;
        } else if (nums.length == 1) {
            return 1;
        } else {
            int number = 0;
            for (int i = 1; i < nums.length; i++) {
                if (nums[number] != nums[i]) {
                    number ++;
                    nums[number] = nums[i];
                }
            }
            return ++number;
        }
    }
  public static void main(String[] args) {
         int[] nums = {1,1,2,2,3,3,4,4,5,5};
         int i = removeDuplicates(nums);
         System.out.println(i);
     }