Merge pull request #1857 from PeixiZ/master

添加C#程序，使用三指针感觉会更形象表述链表翻转

problems/0206.翻转链表.md

@@ -628,6 +628,43 @@ impl Solution {
     }
 }
 ```
+C#:
+三指针法， 感觉会更直观：
+
+```cs
+public LinkNumbers Reverse()
+{
+    ///用三指针，写的过程中能够弥补二指针在翻转过程中的想象
+    LinkNumbers pre = null;
+    var move = root;
+    var next = root;
+
+    while (next != null)
+    {
+        next = next.linknext;
+        move.linknext = pre;
+        pre = move;
+        move = next;
+    }
+    root = pre;
+    return root;
+}
+
+///LinkNumbers的定义
+public class LinkNumbers
+{
+    /// <summary>
+    /// 链表值
+    /// </summary>
+    public int value { get; set; }
+
+    /// <summary>
+    /// 链表指针
+    /// </summary>
+    public LinkNumbers linknext { get; set; }
+}
+```
+
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