完善所以c#相关的文档和代码

codes/csharp/chapter_computational_complexity/leetcode_two_sum.cs

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+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace hello_algo.chapter_computational_complexity
+{
+    class SolutionBruteForce
+    {
+        public int[] twoSum(int[] nums, int target)
+        {
+            int size = nums.Length;
+            // 两层循环，时间复杂度 O(n^2)
+            for (int i = 0; i < size - 1; i++)
+            {
+                for (int j = i + 1; j < size; j++)
+                {
+                    if (nums[i] + nums[j] == target)
+                        return new int[] { i, j };
+                }
+            }
+            return new int[0];
+        }
+    }
+
+    class SolutionHashMap
+    {
+        public int[] twoSum(int[] nums, int target)
+        {
+            int size = nums.Length;
+            // 辅助哈希表，空间复杂度 O(n)
+            Dictionary<int, int> dic = new();
+            // 单层循环，时间复杂度 O(n)
+            for (int i = 0; i < size; i++)
+            {
+                if (dic.ContainsKey(target - nums[i]))
+                {
+                    return new int[] { dic[target - nums[i]], i };
+                }
+                dic.Add(nums[i], i);
+            }
+            return new int[0];
+        }
+    }
+
+    public class leetcode_two_sum
+    {
+        [Test]
+        public void Test()
+        {
+            // ======= Test Case =======
+            int[] nums = { 2, 7, 11, 15 };
+            int target = 9;
+
+            // ====== Driver Code ======
+            // 方法一
+            SolutionBruteForce slt1 = new SolutionBruteForce();
+            int[] res = slt1.twoSum(nums, target);
+            Console.WriteLine("方法一 res = " + string.Join(",", res));
+            // 方法二
+            SolutionHashMap slt2 = new SolutionHashMap();
+            res = slt2.twoSum(nums, target);
+            Console.WriteLine("方法二 res = " + string.Join(",", res));
+        }
+    }
+}