leetcode442

public class Solution {
    Dictionary<int, int> dic = new Dictionary<int, int>();
        public IList<int> FindDuplicates(int[] nums)
        {
            var list = new List<int>();
            foreach (var n in nums)
            {
                if (!dic.ContainsKey(n))
                {
                    dic.Add(n, 1);
                }
                else
                {
                    list.Add(n);
                }
            }
            return list;
        }
}

https://leetcode.com/problems/find-all-duplicates-in-an-array/#/description