js单项链表封装

原创已于 2024-04-09 16:52:48 修改 · 382 阅读

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#链表 #数据结构

于 2024-01-16 22:29:02 首次发布

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本文介绍了JavaScript中链表的数据结构，与数组相比，链表具有动态扩容优势，支持在任意位置插入和删除数据，但不支持随机访问。通过示例展示了链表的基本操作，如添加、插入、获取、查找和修改元素等。

1.链表和数组一样，用于存储一系列元素，但是链表和数组的实现机制完全不同
2.数组：要存储多个元素，数据可能是常用的数据结构，但数组有很多缺点，数组的创建通常需要申请一段连续的内存空间(一整块的内存)，并且大小是固定的，所以当前数组不能满足容量需求时，需要扩容。
数组在开头或中间插入数据的成本很高，需要进行大量的元素的位移。

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>单向链表</title>
</head>

<body>
  <script>
    function LinkedList() {
      function Node(data, next = null) {
        this.data = data
        this.next = next
      }
      this.head = null
      this.len = 0
      // 节点新增
      LinkedList.prototype.append = function (data) {
        let newNode = new Node(data) // 创建新节点
        if (this.len === 0) { // 第一个节点直接加入
          this.head = newNode
        } else {
          let current = this.head
          while (current.next) { // 寻找最后一个节点
            current = current.next
          }
          current.next = newNode
        }
        this.len += 1
      }
      LinkedList.prototype.toString = function () {
        let current = this.head
        let listString = ''
        while (current) {
          listString += current.data + ' '
          current = current.next
        }
        return listString.trim();
      }
      // 任意位置插入数据
      LinkedList.prototype.insert = function (position, data) {
        // 负数越界，长度越界判断
        if (position < 0 || position > this.len) return false
        let newNode = new Node(data)
        if (position === 0) {
          newNode.next = this.head
          this.head = newNode
        } else {
          let index = 0
          let current = this.head
          let previous = null
          while (index++ < position) {
            previous = current
            current = current.next
          }
          newNode.next = current
          previous.next = newNode
        }
        this.len += 1
        return true
      }

      LinkedList.prototype.get = function (position, data) {
        // 越界判断
        if (position < 0 || position >= this.len) return null
        let current = this.head
        let index = 0
        while (index++ < current) {
          current = current.next
        }
        return current.data
      }

      LinkedList.prototype.indexOf = function (data) {
        let current = this.head
        let index = 0
        while (current) {
          if (current.data === data) {
            return index
          }
          current = current.next
          index += 1
        }
        return -1
      }
      LinkedList.prototype.update = function (position, newData) {
        if (position < 0 || position > this.len) return false
        let current = this.head
        let index = 0
        while (index++ < position) {
          current = current.next
        }
        current.data = newData
        return true
      }
      LinkedList.prototype.removeAt = function (position) {
        if (position < 0 || position > this.len) return false
        let current = this.head
        let index = 0
        if (position === 0) {
          this.head = this.head.next
        } else {
          let index = 0
          let previous = null
          while (index++ < position) {
            previous = current
            current = current.next
          }
          previous.next = current.next
        }
        this.len -= 1
        return current.data
      }
      LinkedList.prototype.remove = function (data) {
        let position = this.indexOf(data)
        return this.removeAt(position)
      }
      LinkedList.prototype.isEmpty = function () {
        return this.len === 0
      }
      LinkedList.prototype.size = function () {
        return this.len
      }
    }



    let linkedList = new LinkedList();

    // Test case 1: append
    linkedList.append('A');
    linkedList.append('B');
    linkedList.append('C');
    console.log('After appending: ', linkedList.toString()); // Output: 'A B C'

    // Test case 2: insert
    linkedList.insert(1, 'D');
    console.log('After inserting at position 1: ', linkedList.toString()); // Output: 'A D B C'

    // Test case 3: get
    console.log('Element at position 2: ', linkedList.get(2)); // Output: 'B'

    // Test case 4: indexOf
    console.log('Index of element "D": ', linkedList.indexOf('D')); // Output: 1

    // Test case 5: update
    linkedList.update(2, 'E');
    console.log('After updating element at position 2: ', linkedList.toString()); // Output: 'A D E C'

    // Test case 6: removeAt
    linkedList.removeAt(1);
    console.log('After removing at position 1: ', linkedList.toString()); // Output: 'A E C'

    // Test case 7: remove
    linkedList.remove('A');
    console.log('After removing element "A": ', linkedList.toString()); // Output: 'E C'

    // Test case 8: isEmpty
    console.log('Is the linked list empty? ', linkedList.isEmpty()); // Output: false

    // Test case 9: size
    console.log('Size of the linked list: ', linkedList.size()); // Output: 2
  </script>
</body>

</html>