---
title: leetcode - Reverse Linked List
date: 2023-02-18
public: true
summary: 反转链表，这次你一定要懂
tags:
    - Reverse Linked List
    - 反转链表
    - leetcode
---

> [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/description/)，这个不会建议回炉重造了(说的就是我)。

## recursive

+ Base Case: Rather than a **condition** to keep running, recursive algorithms reach a point to **stop and return**. This point is commonly referred to as the **base case**.
+ Each time you call the function, an argument must change. One argument in particular should be changing *towards* the **base case**.
+ **Establish your base case**. Figure out when the recursion ends! Without a place to stop you’ll wind up overflowing the [call stack](https://en.wikipedia.org/wiki/Call_stack).

```typescript
/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */

function reverseList(head: ListNode | null): ListNode | null {
  // base case, breaking recursive loop
  if (head === null || head.next === null) return head;
  const newHead = reverseList(head.next);
  head.next.next = head;
  head.next = null;
  return newHead;
};
```

## two pointers

```typescript
/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */

function reverseList(head: ListNode | null): ListNode | null {
  let prev = null;
  let cur = head;
  while (cur !== null) {
    const next = cur.next;
    cur.next = prev;
    prev = cur;
    cur = next;
  }
  return prev;
};
```




leetcode - Reverse Linked List

---
title: leetcode - Reverse Linked List
date: 2023-02-18
public: true
summary: 反转链表，这次你一定要懂
posterId: 47879
tags:
    - Reverse Linked List
    - 反转链表
    - leetcode
---

> [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/description/)，这个不会建议回炉重造了(说的就是我)。

## recursive

+ Base Case: Rather than a **condition** to keep running, recursive algorithms reach a point to **stop and return**. This point is commonly referred to as the **base case**.
+ Each time you call the function, an argument must change. One argument in particular should be changing *towards* the **base case**.
+ **Establish your base case**. Figure out when the recursion ends! Without a place to stop you’ll wind up overflowing the [call stack](https://en.wikipedia.org/wiki/Call_stack).

```typescript
/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */

function reverseList(head: ListNode | null): ListNode | null {
  // base case, breaking recursive loop
  if (head === null || head.next === null) return head;
  const newHead = reverseList(head.next);
  head.next.next = head;
  head.next = null;
  return newHead;
};
```

## two pointers

```typescript
/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */

function reverseList(head: ListNode | null): ListNode | null {
  let prev = null;
  let cur = head;
  while (cur !== null) {
    const next = cur.next;
    cur.next = prev;
    prev = cur;
    cur = next;
  }
  return prev;
};
```




leetcode - Reverse Linked List @ Thu, Feb 23, 2023 7:17 PM		leetcode - Reverse Linked List @ Thu, Feb 23, 2023 9:10 PM
	Expand 2 lines ...
3	`date: 2023-02-18`	3		`date: 2023-02-18`
4	`public: true`	4		`public: true`
5	`summary: 反转链表，这次你一定要懂`	5		`summary: 反转链表，这次你一定要懂`
		6	+	`posterId: 47879`
6	`tags:`	7		`tags:`
7	`- Reverse Linked List`	8		`- Reverse Linked List`
8	`- 反转链表`	9		`- 反转链表`
	Expand 61 lines ...