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链表的实现js

2026-01-30 21:57:10JavaScript

链表的基本概念

链表是一种线性数据结构，由一系列节点组成，每个节点包含数据部分和指向下一个节点的指针。与数组不同，链表在内存中是非连续存储的，动态增删节点更高效。

单链表的实现

class ListNode {
  constructor(val) {
    this.val = val;
    this.next = null;
  }
}

class LinkedList {
  constructor() {
    this.head = null;
    this.size = 0;
  }

  // 在链表尾部添加节点
  append(val) {
    const newNode = new ListNode(val);
    if (!this.head) {
      this.head = newNode;
    } else {
      let current = this.head;
      while (current.next) {
        current = current.next;
      }
      current.next = newNode;
    }
    this.size++;
  }

  // 在特定位置插入节点
  insertAt(val, index) {
    if (index < 0 || index > this.size) return false;
    const newNode = new ListNode(val);
    if (index === 0) {
      newNode.next = this.head;
      this.head = newNode;
    } else {
      let current = this.head;
      for (let i = 0; i < index - 1; i++) {
        current = current.next;
      }
      newNode.next = current.next;
      current.next = newNode;
    }
    this.size++;
    return true;
  }

  // 删除特定位置的节点
  removeFrom(index) {
    if (index < 0 || index >= this.size) return null;
    let removedNode;
    if (index === 0) {
      removedNode = this.head;
      this.head = this.head.next;
    } else {
      let current = this.head;
      for (let i = 0; i < index - 1; i++) {
        current = current.next;
      }
      removedNode = current.next;
      current.next = current.next.next;
    }
    this.size--;
    return removedNode.val;
  }

  // 获取链表长度
  getSize() {
    return this.size;
  }

  // 打印链表
  print() {
    let current = this.head;
    let str = '';
    while (current) {
      str += current.val + ' -> ';
      current = current.next;
    }
    str += 'null';
    console.log(str);
  }
}

双向链表的实现

双向链表每个节点包含指向前驱和后继的指针，支持双向遍历。

class DoublyListNode {
  constructor(val) {
    this.val = val;
    this.prev = null;
    this.next = null;
  }
}

class DoublyLinkedList {
  constructor() {
    this.head = null;
    this.tail = null;
    this.size = 0;
  }

  append(val) {
    const newNode = new DoublyListNode(val);
    if (!this.head) {
      this.head = newNode;
      this.tail = newNode;
    } else {
      newNode.prev = this.tail;
      this.tail.next = newNode;
      this.tail = newNode;
    }
    this.size++;
  }

  insertAt(val, index) {
    if (index < 0 || index > this.size) return false;
    const newNode = new DoublyListNode(val);
    if (index === 0) {
      if (!this.head) {
        this.head = newNode;
        this.tail = newNode;
      } else {
        newNode.next = this.head;
        this.head.prev = newNode;
        this.head = newNode;
      }
    } else if (index === this.size) {
      this.tail.next = newNode;
      newNode.prev = this.tail;
      this.tail = newNode;
    } else {
      let current = this.head;
      for (let i = 0; i < index - 1; i++) {
        current = current.next;
      }
      newNode.next = current.next;
      newNode.prev = current;
      current.next.prev = newNode;
      current.next = newNode;
    }
    this.size++;
    return true;
  }
}

环形链表的实现

环形链表的尾节点指向头节点，形成闭环。

class CircularLinkedList {
  constructor() {
    this.head = null;
    this.size = 0;
  }

  append(val) {
    const newNode = new ListNode(val);
    if (!this.head) {
      this.head = newNode;
      newNode.next = this.head;
    } else {
      let current = this.head;
      while (current.next !== this.head) {
        current = current.next;
      }
      current.next = newNode;
      newNode.next = this.head;
    }
    this.size++;
  }
}