448. [LeetCode]Find All Numbers Disappeared in an Array

原文地址

class Solution(object):
    def findDisappearedNumbers(self, nums):
        """
        :type nums: List[int]
        :rtype: List[int]
        """
        # For each number i in nums,
        # we mark the number that i points as negative.
        # Then we filter the list, get all the indexes
        # who points to a positive number
        for i in range(len(nums)):
            index = abs(nums[i]) - 1
            nums[index] = - abs(nums[index])

        return [i + 1 for i in range(len(nums)) if nums[i] > 0]

这道题有两个注意点：
1. 可以使用正负号，在不改变数列中，数的大小的情况下，对数列中的数，进行标记
2. 注意返回值的形式