README_EN.md

448. Find All Numbers Disappeared in an Array

中文文档

Description

Given an array nums of n integers where nums[i] is in the range [1, n], return an array of all the integers in the range [1, n] that do not appear in nums.

 

Example 1:

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

Example 2:

Input: nums = [1,1]
Output: [2]

 

Constraints:

• n == nums.length
• 1 <= n <= 105
• 1 <= nums[i] <= n

 

Follow up: Could you do it without extra space and in O(n) runtime? You may assume the returned list does not count as extra space.

Solutions

Python3

class Solution:
    def findDisappearedNumbers(self, nums: List[int]) -> List[int]:
        for num in nums:
            index = abs(num) - 1
            if nums[index] > 0:
                nums[index] *= -1
        res = []
        for i, v in enumerate(nums):
            if v > 0:
                res.append(i + 1)
        return res

Java

class Solution {
    public List<Integer> findDisappearedNumbers(int[] nums) {
        int n = nums.length;
        for (int i = 0; i < n; ++i) {
            int index = Math.abs(nums[i]) - 1;
            if (nums[index] > 0) {
                nums[index] *= -1;
            }
        }
        List<Integer> res = new ArrayList<>();
        for (int i = 0; i < n; ++i) {
            if (nums[i] > 0) {
                res.add(i + 1);
            }
        }
        return res;
    }
}

...