Find All Numbers Disappeared in an Array
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;
}
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