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