Import C# solutions from https://github.com/kfstorm/LeetCode

Author: kfstorm

solution/0001.Two Sum/Solution.cs

@@ -0,0 +1,20 @@
+using System.Collections.Generic;
+
+public class Solution {
+    public int[] TwoSum(int[] nums, int target) {
+        var dict = new Dictionary<int, int>();
+        for (var i = 0; i < nums.Length; ++i)
+        {
+            int index;
+            if (dict.TryGetValue(target - nums[i], out index))
+            {
+                return new [] { index + 1, i + 1};
+            }
+            if (!dict.ContainsKey(nums[i]))
+            {
+                dict.Add(nums[i], i);
+            }
+        }
+        return null;
+    }
+}

solution/0002.Add Two Numbers/Solution.cs

@@ -0,0 +1,26 @@
+public class Solution {
+    public ListNode AddTwoNumbers(ListNode l1, ListNode l2) {
+        return AddInternal(l1, l2, false);
+    }
+    
+    private ListNode AddInternal(ListNode l1, ListNode l2, bool plusOne)
+    {
+        if (l1 == null && l2 == null)
+        {
+            if (plusOne)
+            {
+                return new ListNode(1);
+            }
+            return null;
+        }
+        
+        var val = (l1 == null ? 0 : l1.val) + (l2 == null ? 0 : l2.val) + (plusOne ? 1 : 0); 
+        plusOne = val >= 10;
+        val %= 10;
+        return new ListNode(val)
+        {
+            //next = AddInternal(l1?.next, l2?.next, plusOne);
+            next = AddInternal(l1 == null ? null : l1.next, l2 == null ? null : l2.next, plusOne)
+        };
+    }
+}