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Find All Numbers Disappeared in an Array

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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.

class Solution {
    public List<Integer> findDisappearedNumbers(int[] nums) {
        Set<Integer> set = new HashSet<>();
        for (int val : nums) {
            set.add(val);
        }
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 1; i <= nums.length; i++) {
            if (!set.contains(i)) {
                list.add(i);
            }
        }
        return list;
    }
}

Posted by Jamie Meyer 25 days ago