Add C# solution of 350

Author: Jahir509

solution/0300-0399/0350.Intersection of Two Arrays II/README_EN.md

@@ -213,6 +213,45 @@ class Solution {
 }
 ```
 
+### **C#**
+```c#
+public class Solution {
+    public int[] Intersect(int[] nums1, int[] nums2) {
+        HashSet<int> hs1 = new HashSet<int>(nums1.Concat(nums2).ToArray());
+        Dictionary<int,int> dict = new Dictionary<int,int>();
+        List<int> result = new List<int>();
+
+        foreach(int value in hs1){
+            dict[value] = 0;
+        }
+
+        foreach(int value in nums1)
+        {
+            if(dict.ContainsKey(value))
+            {
+                dict[value]+=1;
+            }
+            else
+            {
+                dict[value] = 1;
+            }
+        }
+
+        foreach(int value in nums2)
+        {
+            if(dict[value] > 0)
+            {
+                result.Add(value);
+                dict[value] -=1;
+            }
+        }
+
+        return result.ToArray();
+    }
+}
+```
+
+
 ### **...**
 
 ```

solution/0300-0399/0350.Intersection of Two Arrays II/Solution.cs

@@ -0,0 +1,34 @@
+public class Solution {
+    public int[] Intersect(int[] nums1, int[] nums2) {
+        HashSet<int> hs1 = new HashSet<int>(nums1.Concat(nums2).ToArray());
+        Dictionary<int,int> dict = new Dictionary<int,int>();
+        List<int> result = new List<int>();
+
+        foreach(int value in hs1){
+            dict[value] = 0;
+        }
+
+        foreach(int value in nums1)
+        {
+            if(dict.ContainsKey(value))
+            {
+                dict[value]+=1;
+            }
+            else
+            {
+                dict[value] = 1;
+            }
+        }
+
+        foreach(int value in nums2)
+        {
+            if(dict[value] > 0)
+            {
+                result.Add(value);
+                dict[value] -=1;
+            }
+        }
+
+        return result.ToArray();
+    }
+}