public int removeDuplicates(int[] nums){
    if (nums.length = 0) return 0;
    
    int i = 0;
    for (int j = 1; j < nums.length; j++) {
      if (nums[j] != nums[i]) {
        i++;
        nums[i] = nums[j];
      }
    }
    return i + 1;
}