Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.
Find all the elements of [1, n] inclusive that do not appear in this array.
Could you do it without extra space and in O(n) runtime? You may assume the returned list does not count as extra space.
Example:
Input: [4,3,2,7,8,2,3,1] Output: [5,6]
在一个1到n的数组中，找到没有的数字并存放到一个数组中返回
class Solution:
def findDisappearedNumbers(self, nums):
"""
:type nums: List[int]
:rtype: List[int]
"""
s = set(nums)
res = []
for x in range(1, len(nums) + 1):
if x not in s:
res.append(x)
return res
l = [4, 3, 2, 7, 8, 2, 3, 1]
print(Solution.findDisappearedNumbers(Solution, l))