leetcode448--Find All Numbers Disappeared in an Array

# 小郑之家~

### 题目

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]



class Solution(object):
def findDisappearedNumbers(self, nums):
"""
:type nums: List[int]
:rtype: List[int]
"""

ret = []
ret[:] = nums

for x in nums:
ret[x-1]=0

result = []
for i in range(len(nums)):
if ret[i]>0:
result.append(i+1)

return result



class Solution(object):
def findDisappearedNumbers(self, nums):
"""
:type nums: List[int]
:rtype: List[int]
"""

for x in nums:
if nums[abs(x)-1] < 0:
continue
else:
nums[abs(x)-1] *= -1

ret = []

for i in range(len(nums)):
if nums[i]>0:
ret.append(i+1)

return ret