find-all-numbers-disappeared-in-an-array

#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.
#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]
        """
        for v in nums:
            index = int(v) - 1
            nums[index] += 0.4
        return [i+1 for i in xrange(len(nums)) if nums[i] == int(nums[i])]