前端知识学习24.3.19

如何反转一个链表

三个指针，一个指向头节点，另外两个用来指向头节点前后两个节点的位置

// 定义链表节点类
class ListNode {
  constructor(val) {
    this.val = val;
    this.next = null;
  }
}

// 定义反转链表函数
function reverseLinkedList(head) {
  let prev = null;
  let current = head;
  
  while (current !== null) {
    const nextTemp = current.next;
    current.next = prev;
    prev = current;
    current = nextTemp;
  }
  
  return prev; // 返回反转后的头节点
}

// 示例用法
const head = new ListNode(1);
head.next = new ListNode(2);
head.next.next = new ListNode(3);
head.next.next.next = new ListNode(4);
head.next.next.next.next = new ListNode(5);

console.log("原始链表:");
let current = head;
while (current !== null) {
  console.log(current.val);
  current = current.next;
}

const reversedHead = reverseLinkedList(head);

console.log("反转后的链表:");
let reversedCurrent = reversedHead;
while (reversedCurrent !== null) {
  console.log(reversedCurrent.val);
  reversedCurrent = reversedCurrent.next;
}