数据结构与算法JavaScript描述练习------第3章列表

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#javascript #算法

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1. 增加一个向列表中插入元素的方法，该方法只在待插元素大于列表中的所有元素时才执行插入操作。这里的大于有多重含义，对于数字，它是指数值上的大小；对于字母，它是指在字母表中出现的先后顺序。

function isGreaterThan(a, b) {
	if (typeof a === 'number' && typeof b === 'number') {
		return a > b;
	} else if (typeof a === 'string' && typeof b === 'string') {
		return a.localeCompare(b) > 0;
	} else {
		throw new Error('Unsupported data type');
	}
}

function insertIfGreaterThanAll(element) {
	for (var i = 0; i < this.dataStore.length; i++) {
		if (!isGreaterThan(element, this.dataStore[i])) {
			return false;
		}
	}
	this.append(element);
	return true;
}

2. 增加一个向列表中插入元素的方法，该方法只在待插元素小于列表中的所有元素时才执行插入操作。

function isLessThan(a, b) {
	if (typeof a === 'number' && typeof b === 'number') {
		return a < b;
	} else if (typeof a === 'string' && typeof b === 'string') {
		return a.localeCompare(b) < 0;
	} else {
		throw new Error('Unsupported data type');
	}
}

function insertIfLessThanAll(element) {
	for (var i = 0; i < this.dataStore.length; i++) {
		if (!isLessThan(element, this.dataStore[i])) {
			return false;
		}
	}
	this.append(element);
	return true;
}

3. 创建 Person 类，该类用于保存人的姓名和性别信息。创建一个至少包含 10 个 Person 对象的列表。写一个函数显示列表中所有拥有相同性别的人。

function Person(name, gender) {
    this.name = name;
    this.gender = gender;
}

function displayPeopleByGender(peopleList, gender) {
	for (peopleList.front(); peopleList.currPos() < peopleList.length(); peopleList.next()) {
		if (peopleList.getElement().gender === gender) {
			console.log(gender + "性：" + peopleList.getElement().name);
		}
	}
}


var list = new List();
list.append(new Person("张三", "男"));
list.append(new Person("李四", "女"));
list.append(new Person("王五", "男"));
list.append(new Person("赵六", "女"));
list.append(new Person("刘七", "男"));
list.append(new Person("陈八", "女"));
list.append(new Person("周九", "男"));
list.append(new Person("吴十", "女"));
list.append(new Person("郑十一", "男"));
list.append(new Person("孙十二", "女"));
displayPeopleByGender(list, "男");
displayPeopleByGender(list, "女");

4. 修改本章的影碟租赁程序，当一部影片检出后，将其加入一个已租影片列表。每当有客户检出一部影片，都显示该列表中的内容。

function checkOut(name, movie, filmList, customerList, rentList) {
	if (filmList.contains(movie)) {
		var c = new Customer(name, movie);
		customerList.append(c);
		rentList.append(movie);
		filmList.remove(movie);
		console.log("Rented movies: ");
        displayList(rentList);
	} else {
		console.log(movie + " is not available.");
	}
}

5. 为影碟租赁程序创建一个 check-in() 函数，当客户归还一部影片时，将该影片从已租列表中删除，同时添加到现有影片列表中。

function checkIn(name, movie, filmList, customerList, rentList) {
	if (rentList.contains(movie)) {
		rentList.remove(movie);
		filmList.append(movie);
		console.log(movie + " has been returned.\n");
		console.log("rent movies: \n");
		displayList(rentList);
		for (customerList.front(); customerList.currPos() < customerList.length(); customerList.next()) {
			if (customerList.getElement().movie == movie) {
				customerList.remove(customerList.getElement());
			}
		}
		console.log("\nCustomer Rentals: \n");
		displayList(customers);
	} else {
		console.log(movie + " is not rented.\n");
	}
}

List不是JavaScript的内置类型，记录一下数组实现的List对象：


function List() { 
	this.listSize = 0; 
	this.pos = 0; 
	this.dataStore = []; 
	this.clear = clear; 
	this.find = find; 
	this.toString = toString; 
	this.insert = insert; 
	this.append = append; 
	this.remove = remove; 
	this.front = front; 
	this.end = end; 
	this.prev = prev; 
	this.next = next; 
	this.length = length; 
	this.currPos = currPos; 
	this.moveTo = moveTo; 
	this.getElement = getElement; 
	this.length = length; 
	this.contains = contains; 
	this.insertIfGreaterThanAll = insertIfGreaterThanAll;
	this.insertIfLessThanAll = insertIfLessThanAll;
}

function append(element) { 
	this.dataStore[this.listSize++] = element; 
}
function find(element) { 
	for (var i = 0; i < this.dataStore.length; ++i) { 
		if (this.dataStore[i] == element) { 
			return i; 
		} 
	} 
	return -1; 
}
function remove(element) { 
	var foundAt = this.find(element); 
	if (foundAt > -1) { 
		this.dataStore.splice(foundAt,1); 
		--this.listSize; 
		return true; 
	} 
	return false; 
}
function length() { 
	return this.listSize; 
}
function toString() { 
	return this.dataStore; 
}
function insert(element, after) { 
	var insertPos = this.find(after); 
	if (insertPos > -1) { 
		this.dataStore.splice(insertPos+1, 0, element); 
		++this.listSize; 
		return true; 
	} 
	return false; 
}
function clear() { 
	delete this.dataStore; 
	this.dataStore = []; 
	this.listSize = this.pos = 0; 
}
function contains(element) { 
	for (var i = 0; i < this.dataStore.length; ++i) { 
		if (this.dataStore[i] == element) { 
		//if (this.dataStore[i].indexOf(element) >= 0) { 
			return true; 
		} 
	} 
	return false; 
}
function front() { 
	this.pos = 0; 
} 
 
function end() { 
	this.pos = this.listSize-1; 
} 
 
function prev() { 
	if (this.pos > 0) { 
		--this.pos; 
	} 
} 
 
function next() { 
//	if (this.pos < this.listSize-1) { 
		++this.pos; 
//	} 
} 
 
function currPos() { 
	return this.pos; 
} 
 
function moveTo(position) { 
	this.pos = position; 
} 
 
function getElement() { 
	return this.dataStore[this.pos]; 
}

function isGreaterThan(a, b) {
	if (typeof a === 'number' && typeof b === 'number') {
		return a > b;
	} else if (typeof a === 'string' && typeof b === 'string') {
		return a.localeCompare(b) > 0;
	} else {
		throw new Error('Unsupported data type');
	}
}

function isLessThan(a, b) {
	if (typeof a === 'number' && typeof b === 'number') {
		return a < b;
	} else if (typeof a === 'string' && typeof b === 'string') {
		return a.localeCompare(b) < 0;
	} else {
		throw new Error('Unsupported data type');
	}
}

function insertIfGreaterThanAll(element) {
	for (var i = 0; i < this.dataStore.length; i++) {
		if (!isGreaterThan(element, this.dataStore[i])) {
			return false;
		}
	}
	this.append(element);
	return true;
}

function insertIfLessThanAll(element) {
	for (var i = 0; i < this.dataStore.length; i++) {
		if (!isLessThan(element, this.dataStore[i])) {
			return false;
		}
	}
	this.append(element);
	return true;
}







var films = "The Shawshank Redemption（《肖申克的救赎》）                    \n\
	The Godfather（《教父》）                                                   \n \
	The Godfather: Part II（《教父 2》）                                         \n\
	Pulp Fiction（《低俗小说》）                                                 \n\
	The Good, the Bad and the Ugly（《黄金三镖客》）                             \n\
	12 Angry Men（《十二怒汉》 ）                                                \n\
	Schindler’s List（《辛德勒名单》）                                           \n\
	The Dark Knight（《黑暗骑士》）                                              \n\
	The Lord of the Rings: The Return of the King（《指环王：王者归来》）        \n\
	Fight Club（《搏击俱乐部》）                                                \n\
	Star Wars: Episode V - The Empire Strikes Back（《星球大战 5：帝国反击战》）\n\
	One Flew Over the Cuckoo’s Nest（《飞越疯人院》）                           \n\
	The Lord of the Rings: The Fellowship of the Ring（《指环王：护戒使者》）   \n\
	Inception（《盗梦空间》）                                                   \n\
	Goodfellas（《好家伙》）                                                    \n\
	Star Wars（《星球大战》）                                                   \n\
	Seven Samurai（《七武士》）                                                 \n\
	The Matrix（《黑客帝国》）                                                  \n\
	Forrest Gump（《阿甘正传》）                                                \n\
	City of God（《上帝之城》）                                                 \n"
function createArr(file) {
	var arr = file.split("\n");
	for (var i = 0; i < arr.length; i++) {
		arr[i] = arr[i].trim();
	}
	return arr;
}
function Customer(name, movie) {
	this.name = name;
	this.movie = movie;
}
function checkOut(name, movie, filmList, customerList, rentList) {
	if (filmList.contains(movie)) {
		var c = new Customer(name, movie);
		customerList.append(c);
		rentList.append(movie);
		filmList.remove(movie);
		console.log("Rented movies: ");
        displayList(rentList);
	} else {
		console.log(movie + " is not available.");
	}
}
function checkIn(name, movie, filmList, customerList, rentList) {
	if (rentList.contains(movie)) {
		rentList.remove(movie);
		filmList.append(movie);
		console.log(movie + " has been returned.\n");
		console.log("rent movies: \n");
		displayList(rentList);
		for (customerList.front(); customerList.currPos() < customerList.length(); customerList.next()) {
			if (customerList.getElement().movie == movie) {
				customerList.remove(customerList.getElement());
			}
		}
		console.log("\nCustomer Rentals: \n");
		displayList(customers);
	} else {
		console.log(movie + " is not rented.\n");
	}
}
function displayList(list) {
	for (list.front(); list.currPos() < list.length(); list.next()) {
		if (list.getElement() instanceof Customer) {
			console.log(list.getElement()["name"] + ", " + list.getElement()["movie"]);
		} else {
			console.log(list.getElement());
		}
	}
}

var movies = createArr(films);
var movieList = new List();
var customers = new List();
var rentList = new List();
for (var i = 0; i < movies.length; i++) {
	movieList.append(movies[i]);
}
console.log("Available movies: \n");
displayList(movieList);
checkOut("Jane Doe", "The Godfather（《教父》）", movieList, customers, rentList);
console.log("\nCustomer Rentals: \n");
displayList(customers);
console.log("\nAvailable movies: \n");
displayList(movieList);
console.log("\n-----------------------------------------------------\n");
checkIn("Jane Doe", "The Godfather（《教父》）", movieList, customers, rentList);
console.log("Available movies: \n");
displayList(movieList);