带你读《图解算法小抄》一、链表（2）

class LinkedList {
  constructor() {
    this.head = null;
    this.tail = null;
    this.length = 0;
  }
  // 在链表尾部添加新节点
  append(value) {
    const newNode = new Node(value);
    if (!this.head) {
      this.head = newNode;
      this.tail = newNode;
} else {
      this.tail.next = newNode;
      this.tail = newNode;
    }
    this.length++;
  }
  // 在链表指定位置插入新节点
  insertAt(value, index) {
    if (index < 0 || index > this.length) {
      throw new Error("Index out of range");
    }
    const newNode = new Node(value);
    if (index === 0) {
      newNode.next = this.head;
      this.head = newNode;
      if (!this.tail) {
        this.tail = newNode;
      }
    } else if (index === this.length) {
      this.tail.next = newNode;
      this.tail = newNode;
    } else {
      let currentNode = this.head;
      let prevNode = null;
      let currentIndex = 0;
      while (currentIndex < index) {
        prevNode = currentNode;
        currentNode = currentNode.next;
        currentIndex++;
      }
      prevNode.next = newNode;
      newNode.next = currentNode;
    }
    this.length++;
  }
  // 获取指定位置节点的值
  getAt(index) {
    if (index < 0 || index >= this.length) {
      throw new Error("Index out of range");
    }
    let currentNode = this.head;
    let currentIndex = 0;
    while (currentIndex < index) {
      currentNode = currentNode.next;
      currentIndex++;
    }
    return currentNode.value;
  }
  // 删除指定位置的节点
  removeAt(index) {
    if (index < 0 || index >= this.length) {
      throw new Error("Index out of range");
    }
    let currentNode = this.head;
    let prevNode = null;
    let currentIndex = 0;
    if (index === 0) {
      this.head = currentNode.next;
      if (this.length === 1) {
        this.tail = null;
        }
    } else if (index === this.length - 1) {
      while (currentIndex < index) {
        prevNode = currentNode;
        currentNode = currentNode.next;
        currentIndex++;
      }
      prevNode.next = null;
      this.tail = prevNode;
    } else {
      while (currentIndex < index) {
        prevNode = currentNode;
        currentNode = currentNode.next;
        currentIndex++;
      }
      prevNode.next = currentNode.next;
    }
    this.length--;
  }
  // 遍历链表并将节点值以数组形式返回
  toArray() {
    const result = [];
    let currentNode = this.head;
    while (currentNode) {
      result.push(currentNode.value);
      currentNode = currentNode.next;
    }
    return result;
  }
}const linkedList = new LinkedList();
linkedList.append(10);
linkedList.append(20);
linkedList.insertAt(15, 1);
linkedList.removeAt(0);
console.log(linkedList.toArray()); // 输出: [15, 20]