// 封装一个双向链表 function DoublyLinkedList() { // 内部属性 this.head = null; this.tail = null; this.length = 0; // 内部类,存放节点的数据和指针 function Node(data) { this.data = data; this.prev = null; this.next = null; } // append 向链表的最后添加节点 DoublyLinkedList.prototype.append = function (data) { let newNode = new Node(data); if (!this.length) { this.head = newNode; } else { newNode.prev = this.tail; this.tail.next = newNode; } this.tail = newNode; this.length++; return this.length } // toString DoublyLinkedList.prototype.toString = function () { return this.backwardString() } // backwardString 往后遍历得到一个字符串 DoublyLinkedList.prototype.backwardString = function () { let current = this.head; let str = ''; while (current) { str += current.data + ' '; current = current.next; } return str } // forwardString 往前遍历得到一个字符串 DoublyLinkedList.prototype.forwardString = function () { let previous = this.tail; let str = ''; while (previous) { str += previous.data + ' '; previous = previous.prev; } return str } // insert 向链表中插入一个节点 DoublyLinkedList.prototype.insert = function (position, data) { // 越界判断 if (position < 0 || position > this.length) return false; // 创建一个节点 let newNode = new Node(data); // 链表长度为0时 if (this.length == 0) { this.head = newNode; this.tail = newNode; this.length++; return true } // 插入到头部 if (position === 0) { newNode.next = this.head; this.head.prev = newNode; this.head = newNode; } else if (position === this.length) { // 插入到尾部 newNode.prev = this.tail; this.tail.next = newNode; this.tail = newNode; } else { // 插入到其它位置 let current = this.head; let index = 0; while (index++ < position) { current = current.next; } newNode.next = current; newNode.prev = current.prev; current.prev.next = newNode; current.prev = newNode; } this.length++; return true } // removeAt 通过索引删除相应的节点 DoublyLinkedList.prototype.removeAt = function (position) { // 越界判断 if (position < 0 || position >= this.length) return false; let current = this.head; // 如果只有一个节点时 if (this.length === 1) { this.head = null; this.tail = null; this.length--; return current.data } // 删除头部节点 if (position === 0) { this.head = this.head.next; this.head.prev = null; } else if (position === this.length - 1) { // 删除尾部节点 current = this.tail; this.tail = this.tail.prev; this.tail.next = null; this.length--; } else { // 删除其它节点 if (position < this.length / 2) { let index = 0; while (index++ < position) { current = current.next } } else { let index = this.length - 1; while (index-- > position) { current = current.prev } } current.prev.next = current.next; current.next.prev = current.prev; } this.length--; return current.data } // remove 通过信息删除相应的节点 DoublyLinkedList.prototype.remove = function (data) { // 如果只有一个节点时 if (this.length === 1) { this.head = null; this.tail = null; this.length--; return true } // 删除头部节点 if (this.head.data === data) { this.head = this.head.next; this.head.prev = null; this.length--; return true } else if (this.tail.data === data) { // 删除尾部节点 this.tail = this.tail.prev; this.tail.next = null; this.length-- return true } else { // 删除其它节点 let current = this.head; let previous = null; while (current) { previous = current; current = current.next; if (current && current.data === data) { previous.next = current.next; current.next.prev = previous; this.length--; return true } } return false } } // get 通过索引获取相应节点的信息 DoublyLinkedList.prototype.get = function (position) { // 越界判断 if (position < 0 || position >= this.length) return null; if (position < this.length / 2) { // 从前往后遍历 let current = this.head; let index = 0; while (index++ < position) { current = current.next; } return current.data } else { // 从后往前遍历 let current = this.tail; let index = this.length - 1; while (index-- > position) { current = current.prev; } return current.data } } // indexOf 通过节点的信息获取到相应的索引,没有的话返回-1 DoublyLinkedList.prototype.indexOf = function (data) { if (this.tail.data === data) { return this.length - 1 } let current = this.head; let index = 0; while (current) { if (current.data === data) { return index } current = current.next; index++; } return -1; } // update 修改节点的信息 DoublyLinkedList.prototype.update = function (position, newData) { // 越界判断 if (position < 0 || position >= this.length) return false; if (position < this.length / 2) { // 从前往后遍历 let current = this.head; let index = 0; while (index++ < position) { current = current.next } current.data = newData; } else { // 从后往前遍历 let current = this.tail; let index = this.length - 1; while (index-- > position) { current = current.prev; } current.data = newData; } return true; } // isEmpty 判断链表是否为空 DoublyLinkedList.prototype.isEmpty = function () { return this.length == 0 } // size 查看链表的长度 DoublyLinkedList.prototype.size = function () { return this.length } // getHead 获取链表第一个节点 DoublyLinkedList.prototype.getHead = function(){ return this.head.data } // getTail 获取链表最后节点 DoublyLinkedList.prototype.getTail = function(){ return this.tail.data } } // ------ 测试-------- let d_list = new DoublyLinkedList(); d_list.append('帅的'); d_list.append('漂亮'); d_list.append('美德'); d_list.append('人才'); console.log(d_list); console.log(d_list.backwardString()); console.log(d_list.forwardString()); console.log(d_list.insert(0, 'aa')); console.log(d_list.insert(3, 'bb')); console.log(d_list.insert(6, 'cc')); console.log(d_list.toString()); // console.log(d_list.removeAt(6)); // console.log(d_list.get(0)); // console.log(d_list.indexOf('cc')); // console.log(d_list.remove('aa')); // console.log(d_list.remove('bb')); // console.log(d_list.remove('cc')); // console.log(d_list.remove('33')); // console.log(d_list.toString()); // console.log(d_list.update(2, '33')); // console.log(d_list.toString()); // console.log(d_list.isEmpty()); // console.log(d_list.size()); // console.log(d_list.getHead()); // console.log(d_list.getTail());