docs(posts): 新增删除链表倒数第N个节点题解

- 添加灵茶山艾府题单中前后指针章节的题解文件
- 提供两种解法：遍历求长度法和快慢指针法
- 包含Go语言实现代码及配图说明

Author: Marvel-L

posts-img/算法/删除链表倒数第N个节点.png

@@ -0,0 +1,58 @@
+---
+id: lcsaf-remove-nth-node-from-end-of-list
+title: 灵茶山艾府 - 删除链表倒数第N个节点
+excerpt: 
+category: 算法
+tags:
+  - 日常
+  - 链表
+  - 前后指针
+author: Marvel-L
+rank: 黄金
+series: false
+draft: false
+coverImage: / posts-img/算法/删除链表倒数第N个节点.png
+---
+
+
+```go
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+    idx, cur :=0 , head 
+    for cur != nil {
+        idx ++ 
+        cur = cur.Next
+    }
+    length := idx 
+    idx, cur = 0 , head 
+    
+    dummy := &ListNode{Next: head}
+    cur = dummy
+    for cur != nil {
+        if idx + n == length {
+            cur.Next = cur.Next.Next
+        }
+        idx ++ 
+        cur = cur.Next
+    }
+    return dummy.Next 
+}
+```
+
+## 前后指针 Code
+
+```go
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+    dummy := &ListNode{Next:head}
+    left, right := dummy, dummy
+    for range n  {
+        right = right.Next
+    }
+    for right.Next != nil {
+        left = left.Next
+        right = right.Next
+    }
+    left.Next = left.Next.Next
+    return dummy.Next 
+}
+```
+![img.png](img.png)