单链表封装 - 使用JavaScript封装

痛苦就是在蜕变吗

目录

• 链表：
• 链表的特点：
• 单链表：
• • [单链表的封装- JS封装：](#单链表的封装- JS封装：)
• 单链表的应用：
• • 解决回文：
  • 解决击鼓传花：
  • 十进制进制转换其他进制：

链表：

链表就是一种物理存储单元上非连续、非顺序的存储结构，数据元素的逻辑顺序是通过链表中的指针连接次序实现的。链表由一系列结点组成，结点可以在运行时动态的生成。

每个结点包括两个部分：一个是存储数据元素的数据域，另一个是存储下一个结点地址的指针域。

链表的特点：

1. 插入、删除数据效率 O(1)级别（只需要更改指针指向即可），随机访问效率低 O(n)级别 （需要从链头至链尾进行遍历）
2. 和数组相比，内存空间消耗更大，因为每个存储数据的节点都需要额外的空间存储后继指针。

单链表：

每个节点只包含一个指针，即后继指针。

单链表的封装- JS封装：

<script>
  class Node {
    constructor(element) {
      this.element = element;
      this.next = null;
    }
  }

  class LinkedList {
    // #
    constructor() {
      this.count = 0;
      this.head = null;
    }

    // push 添加一个节点
    push (element) {
      const node = new Node(element);

      // header是空
      if (this.head === null) {
        this.head = node;
      } else {
        let current = this.head;
        while (current.next !== null) {
          current = current.next;
        }
        current.next = node;
      }
      this.count++;
    }

    // 指定位置删除 传入索引
    removeAt (index) {
      if (index >= 0 && index < this.count) {
        let current = this.head;
        if (index == 0) {
          this.head = this.head.next;
        } else {
          let previous;
          for (let i = 0; i < index; i++) {
            previous = current;
            current = current.next;
          }
          previous.next = current.next;
        }
        this.count--;
        return current.element;
      }
      return;
    }
    // 指定位置删除-方法二利用getNodeAt(index) 传入索引
    removeAt2 (index) {
      if (index >= 0 && index < this.count) {
        let current = this.head;
        if (index == 0) {
          this.head = this.head.next;
        } else {
          let previous = this.getNodeAt(index - 1);
          current = previous.next;
          previous.next = current.next;
        }
        this.count--;
        return current.element;
      }
      return;
    }

    // 根据索引获得节点node
    getNodeAt (index) {
      if (index >= 0 && index < this.count) {
        let node = this.head;

        for (let i = 0; i < index; i++) {
          node = node.next;
        }
        return node;
      }
      return;
    }

    // 判断是否相等
    equalFn (a, b) {
      // 暴力写法:
      // 也有缺陷 JSON.stringify({a:1,b:2}) !== JSON.stringify({b:2,a:1})
      return JSON.stringify(a) === JSON.stringify(b);
      // 可以使用第三方库
    }

    // 根据元素返回索引
    indexOf (element) {
      let current = this.head;
      for (let i = 0; i < this.count; i++) {
        if (this.equalFn(current.element, element)) {
          return i;
        }
        current = current.next;
      }
    }

    // 直接根据值删除
    remove (element) {
      // 根据数据返回索引的方法
      const index = this.indexOf(element);
      return this.removeAt(index);
    }

    // 指定位置插入内容
    insert (element, index) {
      if (index >= 0 && index <= this.count) {
        const node = new Node(element);
        if (index == 0) {
          const current = this.head;
          node.next = current;
          this.head = node;
        } else {
          const previous = this.getNodeAt(index - 1);
          const current = previous.next;
          previous.next = node;
          node.next = current;
        }
        this.count++;
        return true;
      }
      return false;
    }

    // 判断是否为空
    isEmpty () {
      return this.size() === 0;
    }
    // 判断长度
    size () {
      return this.count;
    }

    // 返回链头
    getHead () {
      return this.head;
    }
  }

  let list = new LinkedList()
</script>

单链表的应用：

解决回文：

举个例子，当初判断回文的时候我们使用的双端队列，在这里使用单链表解决:

<script>
  class Node {
    constructor(element) {
      this.element = element;
      this.next = null;
    }
  }

  class LinkedList {
    // #
    constructor() {
      this.count = 0;
      this.head = null;
    }

    // push 添加一个节点
    push (element) {
      const node = new Node(element);

      // header是空
      if (this.head === null) {
        this.head = node;
      } else {
        let current = this.head;
        while (current.next !== null) {
          current = current.next;
        }
        current.next = node;
      }
      this.count++;
    }

    // 指定位置删除 传入索引
    removeAt (index) {
      if (index >= 0 && index < this.count) {
        let current = this.head;
        if (index == 0) {
          this.head = this.head.next;
        } else {
          let previous;
          for (let i = 0; i < index; i++) {
            previous = current;
            current = current.next;
          }
          previous.next = current.next;
        }
        this.count--;
        return current.element;
      }
      return;
    }
    // 指定位置删除-方法二利用getNodeAt(index) 传入索引
    removeAt2 (index) {
      if (index >= 0 && index < this.count) {
        let current = this.head;
        if (index == 0) {
          this.head = this.head.next;
        } else {
          let previous = this.getNodeAt(index - 1);
          current = previous.next;
          previous.next = current.next;
        }
        this.count--;
        return current.element;
      }
      return;
    }

    // 根据索引获得节点node
    getNodeAt (index) {
      if (index >= 0 && index < this.count) {
        let node = this.head;

        for (let i = 0; i < index; i++) {
          node = node.next;
        }
        return node;
      }
      return;
    }

    // 判断是否相等
    equalFn (a, b) {
      // 暴力写法:
      // 也有缺陷 JSON.stringify({a:1,b:2}) !== JSON.stringify({b:2,a:1})
      return JSON.stringify(a) === JSON.stringify(b);
      // 可以使用第三方库
    }

    // 根据元素返回索引
    indexOf (element) {
      let current = this.head;
      for (let i = 0; i < this.count; i++) {
        if (this.equalFn(current.element, element)) {
          return i;
        }
        current = current.next;
      }
    }

    // 直接根据值删除
    remove (element) {
      // 根据数据返回索引的方法
      const index = this.indexOf(element);
      return this.removeAt(index);
    }

    // 指定位置插入内容
    insert (element, index) {
      if (index >= 0 && index <= this.count) {
        const node = new Node(element);
        if (index == 0) {
          const current = this.head;
          node.next = current;
          this.head = node;
        } else {
          const previous = this.getNodeAt(index - 1);
          const current = previous.next;
          previous.next = node;
          node.next = current;
        }
        this.count++;
        return true;
      }
      return false;
    }

    // 判断是否为空
    isEmpty () {
      return this.size() === 0;
    }
    // 判断长度
    size () {
      return this.count;
    }

    // 返回链头
    getHead () {
      return this.head;
    }
  }
</script>
<script>
  // 使用单链表解决回文问题
  function test (str) {
    const lowstr = str.toLocaleLowerCase().split(" ").join("");

    let list = new LinkedList();

    for (let i = 0; i < lowstr.length; i++) {
      list.push(lowstr[i]);
    }
    let isEqual = true;
    while (list.size() > 1) {
      if (list.removeAt(0) !== list.removeAt(list.size() - 1)) {
        isEqual = false;
        break;
      }
    }
    return isEqual;
  }
  test("D  a   d");
</script>

解决击鼓传花：

举个例子，当初击鼓传花的时候我们使用的队列，在这里使用单链表解决:

<script>
  class Node {
    constructor(element) {
      this.element = element;
      this.next = null;
    }
  }

  class LinkedList {
    // #
    constructor() {
      this.count = 0;
      this.head = null;
    }

    // push 添加一个节点
    push (element) {
      const node = new Node(element);

      // header是空
      if (this.head === null) {
        this.head = node;
      } else {
        let current = this.head;
        while (current.next !== null) {
          current = current.next;
        }
        current.next = node;
      }
      this.count++;
    }

    // 指定位置删除 传入索引
    removeAt (index) {
      if (index >= 0 && index < this.count) {
        let current = this.head;
        if (index == 0) {
          this.head = this.head.next;
        } else {
          let previous;
          for (let i = 0; i < index; i++) {
            previous = current;
            current = current.next;
          }
          previous.next = current.next;
        }
        this.count--;
        return current.element;
      }
      return;
    }
    // 指定位置删除-方法二利用getNodeAt(index) 传入索引
    removeAt2 (index) {
      if (index >= 0 && index < this.count) {
        let current = this.head;
        if (index == 0) {
          this.head = this.head.next;
        } else {
          let previous = this.getNodeAt(index - 1);
          current = previous.next;
          previous.next = current.next;
        }
        this.count--;
        return current.element;
      }
      return;
    }

    // 根据索引获得节点node
    getNodeAt (index) {
      if (index >= 0 && index < this.count) {
        let node = this.head;

        for (let i = 0; i < index; i++) {
          node = node.next;
        }
        return node;
      }
      return;
    }

    // 判断是否相等
    equalFn (a, b) {
      // 暴力写法:
      // 也有缺陷 JSON.stringify({a:1,b:2}) !== JSON.stringify({b:2,a:1})
      return JSON.stringify(a) === JSON.stringify(b);
      // 可以使用第三方库
    }

    // 根据元素返回索引
    indexOf (element) {
      let current = this.head;
      for (let i = 0; i < this.count; i++) {
        if (this.equalFn(current.element, element)) {
          return i;
        }
        current = current.next;
      }
    }

    // 直接根据值删除
    remove (element) {
      // 根据数据返回索引的方法
      const index = this.indexOf(element);
      return this.removeAt(index);
    }

    // 指定位置插入内容
    insert (element, index) {
      if (index >= 0 && index <= this.count) {
        const node = new Node(element);
        if (index == 0) {
          const current = this.head;
          node.next = current;
          this.head = node;
        } else {
          const previous = this.getNodeAt(index - 1);
          const current = previous.next;
          previous.next = node;
          node.next = current;
        }
        this.count++;
        return true;
      }
      return false;
    }

    // 判断是否为空
    isEmpty () {
      return this.size() === 0;
    }
    // 判断长度
    size () {
      return this.count;
    }

    // 返回链头
    getHead () {
      return this.head;
    }
  }
</script>
<script>
  // 击鼓传花
  function game (list, num) {
    let List = new LinkedList();
    for (let i = 0; i < list.length; i++) {
      List.push(list[i]);
    }
    while (List.size() > 1) {
      for (let i = 0; i < num; i++) {
        List.push(List.removeAt(0));
      }
      console.log(List.removeAt(0), '淘汰了');
    }
    console.log('获胜的是：', List.removeAt(0));
  }

  game(['kitty', 'Alice', 'AK', 'Box', 'Whe'], 7);
</script>

十进制进制转换其他进制：

举个例子，当初十进制转换其他进制的时候我们使用的栈，在这里使用单链表解决:

<script>
  class Node {
    constructor(element) {
      this.element = element;
      this.next = null;
    }
  }

  class LinkedList {
    // #
    constructor() {
      this.count = 0;
      this.head = null;
    }

    // push 添加一个节点
    push (element) {
      const node = new Node(element);

      // header是空
      if (this.head === null) {
        this.head = node;
      } else {
        let current = this.head;
        while (current.next !== null) {
          current = current.next;
        }
        current.next = node;
      }
      this.count++;
    }

    // 指定位置删除 传入索引
    removeAt (index) {
      if (index >= 0 && index < this.count) {
        let current = this.head;
        if (index == 0) {
          this.head = this.head.next;
        } else {
          let previous;
          for (let i = 0; i < index; i++) {
            previous = current;
            current = current.next;
          }
          previous.next = current.next;
        }
        this.count--;
        return current.element;
      }
      return;
    }
    // 指定位置删除-方法二利用getNodeAt(index) 传入索引
    removeAt2 (index) {
      if (index >= 0 && index < this.count) {
        let current = this.head;
        if (index == 0) {
          this.head = this.head.next;
        } else {
          let previous = this.getNodeAt(index - 1);
          current = previous.next;
          previous.next = current.next;
        }
        this.count--;
        return current.element;
      }
      return;
    }

    // 根据索引获得节点node
    getNodeAt (index) {
      if (index >= 0 && index < this.count) {
        let node = this.head;

        for (let i = 0; i < index; i++) {
          node = node.next;
        }
        return node;
      }
      return;
    }

    // 判断是否相等
    equalFn (a, b) {
      // 暴力写法:
      // 也有缺陷 JSON.stringify({a:1,b:2}) !== JSON.stringify({b:2,a:1})
      return JSON.stringify(a) === JSON.stringify(b);
      // 可以使用第三方库
    }

    // 根据元素返回索引
    indexOf (element) {
      let current = this.head;
      for (let i = 0; i < this.count; i++) {
        if (this.equalFn(current.element, element)) {
          return i;
        }
        current = current.next;
      }
    }

    // 直接根据值删除
    remove (element) {
      // 根据数据返回索引的方法
      const index = this.indexOf(element);
      return this.removeAt(index);
    }

    // 指定位置插入内容
    insert (element, index) {
      if (index >= 0 && index <= this.count) {
        const node = new Node(element);
        if (index == 0) {
          const current = this.head;
          node.next = current;
          this.head = node;
        } else {
          const previous = this.getNodeAt(index - 1);
          const current = previous.next;
          previous.next = node;
          node.next = current;
        }
        this.count++;
        return true;
      }
      return false;
    }

    // 判断是否为空
    isEmpty () {
      return this.size() === 0;
    }
    // 判断长度
    size () {
      return this.count;
    }

    // 返回链头
    getHead () {
      return this.head;
    }
  }
</script>
<script>
  // 十进制进制转换其他进制
  function convert (decNumber, base) {
    let list = new LinkedList();
    let string = "";
    let number = decNumber;
    let baseString = "0123456789ABCDEF"

    while (number > 0) {
      list.push(number % base);
      number = Math.floor(number / base);
    }
    while (!(list.isEmpty())) {
      string += baseString[list.removeAt(list.size() - 1)];
    }
    return string;
  }
  convert(50, 8)
</script>