LeetCode448 Find All Numbers Disappeared in an Array(java/python)

题目要求:

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]

java solution:

public class solution {
public List<Integer> findDisappearedNumbers(int[] nums) {

//试用建立map的方式进行处理
Set<Integer> set = new HashSet<>();
List<Integer> list = new LinkedList<>();
int index = 1;
for(int i = 0; i < nums.length; i++) {
set.add(nums[i]);
}
for(int i = 0; i < nums.length; i++, index++) {
if(!set.contains(index)) {
list.add(index);
}
}
return list;
}
}

python solution

class Solution(object):
def findDisappearedNumbers(self, nums):
"""
:type nums: List[int]
:rtype: List[int]
"""
return list(i for i in range(1, len(nums) + 1) if i not in nums)

python太猛了,一行就解决了