Initial commit

1. Two Sum/Solution.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace _1._Two_Sum;
+
+public class Solution
+{
+    public int[]? TwoSum(int[] nums, int target)
+    {
+        for (int i = 0; i < nums.Length; i++)
+            for (int j = i+1; j < nums.Length; j++)
+                if (nums[i] + nums[j] == target)
+                    return new int[] { i, j };
+        return null;
+    }
+}