Create csharp LinkedList and its unit test.

codes/csharp/chapter_array_and_linkedlist/LinkedList.cs

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+// File: LinkedList.cs
+// Created Time: 2022-12-16
+// Author: mingXta ([email protected])
+
+using hello_algo.include;
+
+namespace hello_algo.chapter_array_and_linkedlist
+{
+    public class LinkedList
+    {
+        /// <summary>
+        ///在链表的结点 n0 之后插入结点 P
+        /// </summary>
+        public static void Insert(ListNode n0, ListNode P)
+        {
+            ListNode n1 = n0.next;
+            n0.next = P;
+            P.next = n1;
+        }
+
+        /// <summary>
+        /// 删除链表的结点 n0 之后的首个结点
+        /// </summary>
+        public static void Remove(ListNode n0)
+        {
+            if (n0.next == null)
+                return;
+            // n0 -> P -> n1
+            ListNode P = n0.next;
+            ListNode n1 = P.next;
+            n0.next = n1;
+        }
+
+        /// <summary>
+        ///访问链表中索引为 index 的结点
+        /// </summary>
+        public static ListNode Access(ListNode head, int index)
+        {
+            for (int i = 0; i < index; i++)
+            {
+                head = head.next;
+                if (head == null)
+                    return null;
+            }
+            return head;
+        }
+
+        /// <summary>
+        /// 在链表中查找值为 target 的首个结点
+        /// </summary>
+        public static int Find(ListNode head, int target)
+        {
+            int index = 0;
+            while (head != null)
+            {
+                if (head.val == target)
+                    return index;
+                head = head.next;
+                index++;
+            }
+            return -1;
+        }
+    }
+}

codes/csharp/include/ListNode.cs

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+// File: ListNode.cs
+// Created Time: 2022-12-16
+// Author: mingXta ([email protected])
+
+namespace hello_algo.include
+{
+    /// <summary>
+    /// Definition for a singly-linked list node
+    /// </summary>
+    public class ListNode
+    {
+        public int val;
+        public ListNode next;
+
+        /// <summary>
+        /// Generate a linked list with an array
+        /// </summary>
+        /// <param name="x"></param>
+        public ListNode(int x)
+        {
+            val = x;
+        }
+
+        /// <summary>
+        /// Generate a linked list with an array
+        /// </summary>
+        /// <param name="arr"></param>
+        /// <returns></returns>
+        public static ListNode ArrToLinkedList(int[] arr)
+        {
+            ListNode dum = new ListNode(0);
+            ListNode head = dum;
+            foreach (int val in arr)
+            {
+                head.next = new ListNode(val);
+                head = head.next;
+            }
+            return dum.next;
+        }
+
+        /// <summary>
+        /// Get a list node with specific value from a linked list
+        /// </summary>
+        /// <param name="head"></param>
+        /// <param name="val"></param>
+        /// <returns></returns>
+        public static ListNode GetListNode(ListNode head, int val)
+        {
+            while (head != null && head.val != val)
+            {
+                head = head.next;
+            }
+            return head;
+        }
+
+        public override string? ToString()
+        {
+            List<string> list = new();
+            var head = this;
+            while (head != null)
+            {
+                list.Add(head.val.ToString());
+                head = head.next;
+            }
+            return string.Join("->", list);
+        }
+    }
+}

codes/csharp/test/chapter_array_and_linkedlist/LinkedListTest.cs

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+// File: LinkedListTest.cs
+// Created Time: 2022-12-16
+// Author: mingXta ([email protected])
+
+using hello_algo.chapter_array_and_linkedlist;
+using hello_algo.include;
+using NUnit.Framework;
+
+namespace hello_algo.Test.chapter_array_and_linkedlist
+{
+    [TestFixture]
+    internal class LinkedListTest
+    {
+        private ListNode n0;
+        private ListNode n1;
+        private ListNode n2;
+        private ListNode n3;
+        private ListNode n4;
+
+        [SetUp]
+        public void SetUp()
+        {
+            // 初始化各结点
+            n0 = new ListNode(1);
+            n1 = new ListNode(3);
+            n2 = new ListNode(2);
+            n3 = new ListNode(5);
+            n4 = new ListNode(4);
+            // 构建引用指向
+            n0.next = n1;
+            n1.next = n2;
+            n2.next = n3;
+            n3.next = n4;
+        }
+
+        [Test]
+        public void CheckInit()
+        {
+            //检查初始化是否正确
+            Console.WriteLine($"初始化的链表为{n0}");
+            Assert.AreEqual(n0.ToString(), "1->3->2->5->4");
+        }
+
+        [Test]
+        public void TestInsert()
+        {
+            //插入结点
+            LinkedList.Insert(n0, new ListNode(0));
+            Console.WriteLine($"插入结点后的链表为{n0}");
+            Assert.AreEqual(n0.ToString(), "1->0->3->2->5->4");
+        }
+
+        [Test]
+        public void TestRemove()
+        {
+            //删除结点
+            LinkedList.Remove(n0);
+            Console.WriteLine($"删除节点后的链表为{n0}");
+            Assert.AreEqual(n0.ToString(), "1->2->5->4");
+        }
+
+        [Test]
+        public void TestAccess()
+        {
+            //访问结点
+            var node = LinkedList.Access(n0, 3);
+            Console.WriteLine($"链表中索引 3 处的结点的值 ={node.val}");
+            Assert.AreEqual(node.val, 5);
+        }
+
+        [Test]
+        public void TestFind()
+        {
+            //查找结点
+            int index = LinkedList.Find(n0, 2);
+            Console.WriteLine($"链表中值为 2 的结点的索引 = {index}");
+            Assert.AreEqual(index, 2);
+        }
+    }
+}