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题目提供面向对象（OOP）的Java题解，每个题解都封装在独立的类中，体现封装性和可复用性。

news 2026/3/27 5:45:51

1. P5015 标题统计 - 面向对象题解

import java.util.Scanner;/*** 标题统计器类* 用于统计字符串中除空格和换行符外的有效字符数*/
class TitleCounter {private String title;/*** 构造函数* @param title 输入的标题字符串*/public TitleCounter(String title) {this.title = title;}/*** 统计有效字符数* @return 有效字符数量*/public int countValidCharacters() {int count = 0;for (int i = 0; i < title.length(); i++) {char c = title.charAt(i);// 排除空格和换行符if (c != ' ' && c != '\n') {count++;}}return count;}
}public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);// 读取整行输入，包括空格String input = scanner.nextLine();// 创建标题统计器对象TitleCounter counter = new TitleCounter(input);// 计算并输出结果System.out.println(counter.countValidCharacters());scanner.close();}
}

2. P3741 小果的键盘 - 面向对象题解

import java.util.Scanner;/*** VK字符串优化器类* 用于计算通过改变至多一个字符后，字符串中VK出现的最大次数*/
class VKStringOptimizer {private String str;private int n;/*** 构造函数* @param n 字符串长度* @param str 字符串内容*/public VKStringOptimizer(int n, String str) {this.n = n;this.str = str;}/*** 计算字符串中VK出现的次数* @param s 输入字符串* @return VK出现次数*/private int countVK(String s) {int count = 0;for (int i = 0; i < s.length() - 1; i++) {if (s.charAt(i) == 'V' && s.charAt(i + 1) == 'K') {count++;}}return count;}/*** 计算最大VK出现次数* @return 最大VK出现次数*/public int getMaxVKCount() {if (n < 2) {return 0;}int originalCount = countVK(str);int maxCount = originalCount;// 尝试修改每个位置的字符char[] chars = str.toCharArray();for (int i = 0; i < n; i++) {char originalChar = chars[i];// 修改当前字符（V变K，K变V）chars[i] = (chars[i] == 'V') ? 'K' : 'V';// 计算修改后的VK数量String modifiedStr = new String(chars);int currentCount = countVK(modifiedStr);// 更新最大值if (currentCount > maxCount) {maxCount = currentCount;}// 恢复原始字符chars[i] = originalChar;}return maxCount;}
}public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int n = scanner.nextInt();String str = scanner.next();// 创建VK字符串优化器对象VKStringOptimizer optimizer = new VKStringOptimizer(n, str);// 计算并输出最大VK出现次数System.out.println(optimizer.getMaxVKCount());scanner.close();}
}

3. P1421 小玉买文具 - 面向对象题解

import java.util.Scanner;/*** 文具购买计算器类* 用于计算小玉最多能购买的签字笔数量*/
class StationeryCalculator {private int yuan;  // 元private int jiao;  // 角/*** 构造函数* @param yuan 元数* @param jiao 角数*/public StationeryCalculator(int yuan, int jiao) {this.yuan = yuan;this.jiao = jiao;}/*** 计算最多能购买的签字笔数量* @return 最大购买数量*/public int calculateMaxPens() {// 将金额统一为角int totalJiao = yuan * 10 + jiao;// 签字笔单价：1元9角 = 19角int penPrice = 19;// 计算最大购买数量（整除）return totalJiao / penPrice;}
}public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int a = scanner.nextInt();int b = scanner.nextInt();// 创建文具购买计算器对象StationeryCalculator calculator = new StationeryCalculator(a, b);// 计算并输出结果System.out.println(calculator.calculateMaxPens());scanner.close();}
}

4. P1425 小鱼的游泳时间 - 面向对象题解

import java.util.Scanner;/*** 游泳时间计算器类* 用于计算小鱼游泳的总时长*/
class SwimmingTimeCalculator {private int startHour;private int startMinute;private int endHour;private int endMinute;/*** 构造函数* @param startHour 开始小时* @param startMinute 开始分钟* @param endHour 结束小时* @param endMinute 结束分钟*/public SwimmingTimeCalculator(int startHour, int startMinute, int endHour, int endMinute) {this.startHour = startHour;this.startMinute = startMinute;this.endHour = endHour;this.endMinute = endMinute;}/*** 计算游泳总时长* @return 包含小时和分钟的数组 [小时, 分钟]*/public int[] calculateSwimmingTime() {// 将时间转换为总分钟数int startTotalMinutes = startHour * 60 + startMinute;int endTotalMinutes = endHour * 60 + endMinute;// 计算时间差（分钟）int totalMinutes = endTotalMinutes - startTotalMinutes;// 转换为小时和分钟int hours = totalMinutes / 60;int minutes = totalMinutes % 60;return new int[]{hours, minutes};}
}public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int a = scanner.nextInt();int b = scanner.nextInt();int c = scanner.nextInt();int d = scanner.nextInt();// 创建游泳时间计算器对象SwimmingTimeCalculator calculator = new SwimmingTimeCalculator(a, b, c, d);// 计算游泳时长int[] result = calculator.calculateSwimmingTime();// 输出结果System.out.println(result[0] + " " + result[1]);scanner.close();}
}