```
class Solution(object):
def findDisappearedNumbers(self, nums):
"""
:type nums: List[int]
:rtype: List[int]
"""
res = []
nums.sort()
nums.insert(0, 0)
nums.append(len(nums))
i, diff = 1, 0
while i < len(nums):
if nums[i] - nums[i - 1] > 1:
diff = nums[i] - nums[i - 1]
cur = nums[i - 1] + 1
while cur != nums[i]:
res.append(cur)
cur += 1
i += 1
return res
```