LeetCode 448 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.

Example:

Input:[4,3,2,7,8,2,3,1]Output:[5,6]

对数组遍历，如果nums[nums[i]]大于0 就把他乘以-1，本质是做标记哪些数字出现过，最后把值为正的索引输出

class Solution(object):    def findDisappearedNumbers(self, nums):        """        :type nums: List[int]        :rtype: List[int]        """        for i in range(0, len(nums)):            if nums[abs(nums[i])-1] > 0:                nums[abs(nums[i])-1] *= -1        return [x+1 for x in range(0,len(nums)) if nums[x] > 0]