It is a game of numbers. List has numbers from 1 to n, we can use the sum of first n natural numbers to find the missing and duplicated number.

```
class Solution(object):
def findErrorNums(self, nums):
"""
:type nums: List[int]
:rtype: List[int]
"""
n = len(nums)
should_be = n*(n+1)//2
missing = should_be - sum(list(set(nums)))
duplicated = sum(nums)-sum(list(set(nums)))
return [duplicated, missing]
```