Howard的程式筆記

448. Find All Numbers Disappeared in an Array (陣列中找到所有消失的數字)

分類於

題目

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.

給定一個包含n個整數的陣列nums，其中nums[i]的範圍為[1, n]，返回一個陣列，其中包含範圍[1, n]內未在nums中出現的所有整數。

Example 1

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

Example 2

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

Constraints:

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

我的解題

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