From 7ff717e4c2761cb48ef27ff8aa24769753d0b656 Mon Sep 17 00:00:00 2001
From: gameloader <ggwqqo@163.com>
Date: Sun, 3 Mar 2024 11:08:51 +0800
Subject: [PATCH] add leetcode content

---
 content/posts/leetcode.md | 81 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/content/posts/leetcode.md b/content/posts/leetcode.md
index af4c4f9..0d1ceeb 100644
--- a/content/posts/leetcode.md
+++ b/content/posts/leetcode.md
@@ -341,3 +341,84 @@ func abs(val int) int {
 ### 总结
 
 注意一个go的语法问题, 如果在for range循环中两个变量都使用匿名变量, 则应该使用赋值运算符而不是创建并赋值运算符, 即`for _,_ = range slice` 而不是`for _,_ := range slice`. 这很可能是因为匿名变量默认为已经创建好的变量, 不需要再创建匿名变量本身了.
+
+## day6 2024-03-03
+
+### 19. Remove Nth Node From End of List
+
+Given the head of a linked list, remove the nth node from the end of the list and return its head.
+
+![0303SQETJiUaYzaQ](https://testingcf.jsdelivr.net/gh/game-loader/picbase@master/uPic/0303SQETJiUaYzaQ.png)
+
+### 题解
+
+给出了链表头, 要求移除从后到前的第n个节点. 如果想一遍遍历就完成这个任务. 就使用空间换时间, 使用一个数组保存所有的Next指针的值. 然后让倒数第n+1个元素的Next指针指向n个元素的Next指针即可, 注意处理链表只有一个元素的特殊情况.
+
+### 代码
+
+```go
+/**
+ * Definition for singly-linked list.
+ * type ListNode struct {
+ *     Val int
+ *     Next *ListNode
+ * }
+ */
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+    var ptr []*ListNode
+    current := head
+    for current.Next != nil{
+        ptr = append(ptr, current)
+        current = current.Next
+    }
+    ptr = append(ptr, current)
+    if(len(ptr) == 1){
+        return nil
+    }else if len(ptr) == n{
+        return ptr[1]
+    }else{
+        ptr[len(ptr)-n-1].Next = ptr[len(ptr)-n].Next
+        return head
+    }
+}
+```
+
+### 总结
+
+在题解中看到大部分使用的是快慢指针的解法, 快慢指针应该是本题想要的解法, 下面贴一个快慢指针的解法示例
+
+```go
+/**
+ * Definition for singly-linked list.
+ * type ListNode struct {
+ *     Val int
+ *     Next *ListNode
+ * }
+ */
+
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+
+    dummyHead := &ListNode{-1, head}
+
+    cur, prevOfRemoval := dummyHead, dummyHead
+
+    for cur.Next != nil{
+
+        // n step delay for prevOfRemoval
+        if n <= 0 {
+            prevOfRemoval = prevOfRemoval.Next
+        }
+
+        cur = cur.Next
+
+        n -= 1
+    }
+
+    // Remove the N-th node from end of list
+    nthNode := prevOfRemoval.Next
+    prevOfRemoval.Next = nthNode.Next
+
+    return dummyHead.Next
+
+}
+```