const util = require('util');
/**
* 链表节点类
*/
class Node {
constructor (ele) {
this.ele = ele;
this.next = null;
this.prev = null;
}
}
/**
* 链表类
*/
class NodeList {
constructor (ele) {
this.head = null; // 初始化链表的头节点
this.length = 0;
}
/**
* 尾部插入数据
* @param {*} ele
*/
append (ele) {
let newNode = new Node(ele);
let currentNode;
if (this.head === null) {
this.head = newNode;
} else {
currentNode = this.head;
while (currentNode.next) {
currentNode = currentNode.next;
}
currentNode.next = newNode;
newNode.prev = currentNode;
}
this.length++;
}
/**
* 项链表某个位置插入元素
* @param {*} position
* @param {*} ele
*/
insert (position, ele) {
if (position >= 0 && position <= this.length) { let newNode = new Node(ele); let currentNode = this.head; let pre; let index = 0; if (position === 0) { if (currentNode === null) { this.head = newNode; } else { this.head = newNode; newNode.next = currentNode; currentNode.prev = newNode; } } else if (position === this.length) { this.append(ele); return; } else { while (index < position) { pre = currentNode; currentNode = currentNode.next; index++; } newNode.next = currentNode; currentNode.prev = newNode; pre.next = newNode; newNode.prev = pre; } this.length++; } else { return new Error('位置超出范围'); } } removeAt (position) { if (position >= 0 && position < this.length) { let currentNode = this.head; let pre; let index = 0; if (position === 0) { this.head = currentNode.next; } else { while (index < position) { // 1,2,3 pre = currentNode; currentNode = currentNode.next; index++; } pre.next = currentNode.next; if (currentNode && currentNode.next !== null) { currentNode.next.prev = pre; } } this.length--; } else { return new Error('删除位置有误'); } } find (ele) { let currentNode = this.head; let index = 0; while (currentNode) { if (JSON.stringify(currentNode.ele) === JSON.stringify(ele)) { return index; } else { index++; currentNode = currentNode.next; } } return -1; } // 判断链表是否为空 isEmpty () { return this.length === 0; } size () { return this.length; } // 返回头 getHead () { return this.head; } toString () { let current = this.head; let str = ''; while (current) { str += JSON.stringify(current.ele) + ' => ';
current = current.next;
}
return str;
}
}
let A = { name: 'A', age: 10 };

let B = { name: 'B', age: 20 };

let C = { name: 'C', age: 30 };

let D = { name: 'D', age: 40 };

let E = { name: 'E', age: 50 };

let G = { name: 'G', age: 50 };

let nList = new NodeList();

nList.append(A);
nList.append(C);
nList.append(B);
nList.append(D);
nList.append(E);
// console.log(JSON.stringify(nList, null, 2));
nList.insert(5, G);
console.log(' origin: ' + nList);
nList.removeAt(5);
console.log('now: ' + nList);
console.log(util.inspect(nList));