洛谷题目提供**使用面向对象继承概念**的Java解答

洛谷题目提供使用面向对象继承概念的Java解答。每个解答都将展示合理的类层次结构设计。

1. P5740 【深基7.例9】最厉害的学生 (Java OOP 解法)

import java.util.Scanner;// 基类：学生
class Student {protected String name;protected int chinese;protected int math;protected int english;public Student(String name, int chinese, int math, int english) {this.name = name;this.chinese = chinese;this.math = math;this.english = english;}// 计算总分public int getTotal() {return chinese + math + english;}// 获取信息字符串public String getInfo() {return name + " " + chinese + " " + math + " " + english;}
}// 派生类：用于查找最厉害的学生
class TopStudentFinder {private Student topStudent;private int topScore;public TopStudentFinder() {this.topScore = -1;this.topStudent = null;}public void processStudent(Student stu) {int currentScore = stu.getTotal();if (currentScore > topScore) {topScore = currentScore;topStudent = stu;}}public String getTopStudentInfo() {return topStudent != null ? topStudent.getInfo() : "";}
}public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();TopStudentFinder finder = new TopStudentFinder();for (int i = 0; i < n; i++) {String name = sc.next();int chinese = sc.nextInt();int math = sc.nextInt();int english = sc.nextInt();Student stu = new Student(name, chinese, math, english);finder.processStudent(stu);}System.out.println(finder.getTopStudentInfo());sc.close();}
}

2. P5742 【深基7.例11】评等级 (Java OOP 解法)

import java.util.Scanner;// 基类：学生
class Student {protected int id;protected int academic;  // 学业成绩protected int quality;   // 素质拓展成绩public Student(int id, int academic, int quality) {this.id = id;this.academic = academic;this.quality = quality;}// 计算综合分数（避免浮点误差）public int getCompositeScore() {return academic * 7 + quality * 3; // 相当于 (academic*0.7 + quality*0.3) * 10}// 计算总分public int getTotalScore() {return academic + quality;}
}// 派生类：带评级功能的学生
class RatedStudent extends Student {public RatedStudent(int id, int academic, int quality) {super(id, academic, quality);}// 判断是否优秀public boolean isExcellent() {return getTotalScore() > 140 && getCompositeScore() >= 800;}// 获取评级结果public String getRating() {return isExcellent() ? "Excellent" : "Not excellent";}
}public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();for (int i = 0; i < n; i++) {int id = sc.nextInt();int academic = sc.nextInt();int quality = sc.nextInt();RatedStudent student = new RatedStudent(id, academic, quality);System.out.println(student.getRating());}sc.close();}
}

3. P1093 [NOIP2007 普及组] 奖学金 (Java OOP 解法)

import java.util.*;// 基类：学生
class Student {protected int id;protected int chinese;protected int math;protected int english;protected int total;public Student(int id, int chinese, int math, int english) {this.id = id;this.chinese = chinese;this.math = math;this.english = english;this.total = chinese + math + english;}public int getId() { return id; }public int getTotal() { return total; }public int getChinese() { return chinese; }
}// 派生类：可比较的学生（用于排序）
class ComparableStudent extends Student implements Comparable<ComparableStudent> {public ComparableStudent(int id, int chinese, int math, int english) {super(id, chinese, math, english);}@Overridepublic int compareTo(ComparableStudent other) {// 先按总分从高到低排序if (this.total != other.total) {return other.total - this.total;}// 总分相同，按语文成绩从高到低排序if (this.chinese != other.chinese) {return other.chinese - this.chinese;}// 总分和语文都相同，按学号从小到大排序return this.id - other.id;}@Overridepublic String toString() {return id + " " + total;}
}public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();List<ComparableStudent> students = new ArrayList<>();for (int i = 1; i <= n; i++) {int chinese = sc.nextInt();int math = sc.nextInt();int english = sc.nextInt();students.add(new ComparableStudent(i, chinese, math, english));}// 排序Collections.sort(students);// 输出前5名for (int i = 0; i < Math.min(5, students.size()); i++) {System.out.println(students.get(i));}sc.close();}
}

4. P5250 【深基17.例5】木材仓库 (Java OOP 解法)

import java.util.*;// 基类：木材
class Wood implements Comparable<Wood> {protected int length;public Wood(int length) {this.length = length;}public int getLength() {return length;}// 用于TreeSet排序@Overridepublic int compareTo(Wood other) {return Integer.compare(this.length, other.length);}@Overridepublic boolean equals(Object obj) {if (this == obj) return true;if (obj == null || getClass() != obj.getClass()) return false;Wood wood = (Wood) obj;return length == wood.length;}@Overridepublic int hashCode() {return Integer.hashCode(length);}
}// 派生类：木材仓库管理
class WoodWarehouse {private TreeSet<Wood> warehouse;public WoodWarehouse() {warehouse = new TreeSet<>();}// 进货操作public String addWood(int length) {Wood wood = new Wood(length);if (warehouse.contains(wood)) {return "Already Exist";}warehouse.add(wood);return null; // 成功添加不需要输出}// 出货操作public String removeWood(int length) {if (warehouse.isEmpty()) {return "Empty";}Wood target = new Wood(length);// 检查是否有正好长度的木材if (warehouse.contains(target)) {warehouse.remove(target);return String.valueOf(length);}// 没有正好长度的，找最接近的Wood floor = warehouse.floor(target); // 小于等于的最大值Wood ceiling = warehouse.ceiling(target); // 大于等于的最小值Wood toRemove = null;if (floor == null) {toRemove = ceiling;} else if (ceiling == null) {toRemove = floor;} else {int diffFloor = length - floor.getLength();int diffCeiling = ceiling.getLength() - length;if (diffFloor < diffCeiling) {toRemove = floor;} else if (diffFloor > diffCeiling) {toRemove = ceiling;} else {// 距离相等，取较短的一根toRemove = floor;}}if (toRemove != null) {int removedLength = toRemove.getLength();warehouse.remove(toRemove);return String.valueOf(removedLength);}return "Empty";}
}public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int m = sc.nextInt();WoodWarehouse warehouse = new WoodWarehouse();for (int i = 0; i < m; i++) {int op = sc.nextInt();int length = sc.nextInt();if (op == 1) {String result = warehouse.addWood(length);if (result != null) {System.out.println(result);}} else if (op == 2) {System.out.println(warehouse.removeWood(length));}}sc.close();}
}

5. P7176 [COCI2014-2015#4] PRIPREME (Java OOP 解法)

import java.util.*;// 基类：讲解任务
class PresentationTask {protected int timeRequired;public PresentationTask(int timeRequired) {this.timeRequired = timeRequired;}public int getTimeRequired() {return timeRequired;}
}// 派生类：时间调度计算器
class ScheduleCalculator {private List<PresentationTask> tasks;public ScheduleCalculator(List<PresentationTask> tasks) {this.tasks = tasks;}// 计算最少需要的时间public long calculateMinTime() {long totalTime = 0;int maxTime = 0;for (PresentationTask task : tasks) {int time = task.getTimeRequired();totalTime += time;if (time > maxTime) {maxTime = time;}}// 核心逻辑：如果最长的任务时间大于其他所有任务时间之和// 那么最小时间就是 2 * maxTime// 否则就是 totalTimeif (maxTime > totalTime - maxTime) {return 2L * maxTime;} else {return totalTime;}}
}public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();List<PresentationTask> tasks = new ArrayList<>();for (int i = 0; i < n; i++) {int time = sc.nextInt();tasks.add(new PresentationTask(time));}ScheduleCalculator calculator = new ScheduleCalculator(tasks);System.out.println(calculator.calculateMinTime());sc.close();}
}

面向对象设计说明：

1. P5740：使用Student基类和TopStudentFinder处理器类，体现了单一职责原则。
2. P5742：通过RatedStudent继承Student，添加评级功能，展示了继承的扩展性。
3. P1093：ComparableStudent继承Student并实现Comparable接口，便于排序。
4. P5250：设计Wood类和WoodWarehouse仓库管理类，使用TreeSet实现自动排序和快速查找。
5. P7176：通过PresentationTask和ScheduleCalculator分离数据与逻辑，提高代码可维护性。