有四个人坐一起，问第四个人多少岁，他说比第三个人大四岁，问第三个人多少岁，他说比第二个人大四岁，问第二个人多少岁，他说比第一个人大四岁，问第一个人多少岁，他说12岁，问第四个人多少岁？要求用C语言递归实现

好的，我会用C语言递归实现解决这个问题。代码如下：

#include <stdio.h>

int age(int n) {
    if (n == 1) {
        return 12; // 第一个人12岁
    } else {
        return age(n - 1) + 4; // 每个人比前一个人大4岁
    }
}

int main() {
    printf("第四个人的年龄是：%d岁\n", age(4));
    return 0;
}

解析：通过递归函数 `age(n)`，可以求出第n个人的年龄。当 `n=1` 时，返回第一个人的年龄12岁；当 `n>1` 时，递归调用 `age(n-1)`，并加上4岁，即可得到第n个人的年龄。最终在 `main()` 函数中调用 `age(4)`，即可得到第四个人的年龄。

相关问题

设计一个包含5个类的Java程序，名为Person的父类有两个子类，学生类Student和员工类Employee。Employee类有两个子类，教师类Faculty和 职员类Staff。所有人都有编号ID、姓名、地址、电话号码和电子邮件地址。学生类Student有班级状态（大一、大二、大三或大四）。教师类Faculty有主讲课程、上课时间、专业信息。职员类Staff有职务、入职日期信息。覆盖每个类中的toString()方法，输出相应的类名、编号ID和姓名。 编写一个测试程序，随机创建8个Student、Faculty或Staff对象，放在一个数组中，依次调用他们的toString()方法显示信息。并说明如何用dos执行

以下是Java程序代码：

public class Person {
    private String ID;
    private String name;
    private String address;
    private String phoneNumber;
    private String email;

    public Person(String ID, String name, String address, String phoneNumber, String email) {
        this.ID = ID;
        this.name = name;
        this.address = address;
        this.phoneNumber = phoneNumber;
        this.email = email;
    }

    public String getID() {
        return ID;
    }

    public String getName() {
        return name;
    }

    public String getAddress() {
        return address;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public String getEmail() {
        return email;
    }

    @Override
    public String toString() {
        return "Person{" +
                "ID='" + ID + '\'' +
                ", name='" + name + '\'' +
                '}';
    }
}

public class Student extends Person {
    private String classStatus;

    public Student(String ID, String name, String address, String phoneNumber, String email, String classStatus) {
        super(ID, name, address, phoneNumber, email);
        this.classStatus = classStatus;
    }

    public String getClassStatus() {
        return classStatus;
    }

    @Override
    public String toString() {
        return "Student{" +
                "ID='" + getID() + '\'' +
                ", name='" + getName() + '\'' +
                '}';
    }
}

public class Employee extends Person {
    private String position;
    private String hireDate;

    public Employee(String ID, String name, String address, String phoneNumber, String email, String position, String hireDate) {
        super(ID, name, address, phoneNumber, email);
        this.position = position;
        this.hireDate = hireDate;
    }

    public String getPosition() {
        return position;
    }

    public String getHireDate() {
        return hireDate;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "ID='" + getID() + '\'' +
                ", name='" + getName() + '\'' +
                '}';
    }
}

public class Faculty extends Employee {
    private String course;
    private String teachingTime;
    private String major;

    public Faculty(String ID, String name, String address, String phoneNumber, String email, String position, String hireDate, String course, String teachingTime, String major) {
        super(ID, name, address, phoneNumber, email, position, hireDate);
        this.course = course;
        this.teachingTime = teachingTime;
        this.major = major;
    }

    public String getCourse() {
        return course;
    }

    public String getTeachingTime() {
        return teachingTime;
    }

    public String getMajor() {
        return major;
    }

    @Override
    public String toString() {
        return "Faculty{" +
                "ID='" + getID() + '\'' +
                ", name='" + getName() + '\'' +
                '}';
    }
}

public class Staff extends Employee {
    private String duty;

    public Staff(String ID, String name, String address, String phoneNumber, String email, String position, String hireDate, String duty) {
        super(ID, name, address, phoneNumber, email, position, hireDate);
        this.duty = duty;
    }

    public String getDuty() {
        return duty;
    }

    @Override
    public String toString() {
        return "Staff{" +
                "ID='" + getID() + '\'' +
                ", name='" + getName() + '\'' +
                '}';
    }
}

以下是测试程序代码：

import java.util.Random;

public class TestPerson {
    public static void main(String[] args) {
        Person[] people = new Person[8];
        Random random = new Random();

        for (int i = 0; i < 8; i++) {
            int type = random.nextInt(3);
            String ID = "ID" + i;
            String name = "Name" + i;
            String address = "Address" + i;
            String phoneNumber = "PhoneNumber" + i;
            String email = "Email" + i;

            if (type == 0) {
                String classStatus = "大" + (random.nextInt(4) + 1);
                people[i] = new Student(ID, name, address, phoneNumber, email, classStatus);
            } else if (type == 1) {
                String position = "Position" + i;
                String hireDate = "HireDate" + i;
                people[i] = new Staff(ID, name, address, phoneNumber, email, position, hireDate, "Duty" + i);
            } else {
                String position = "Position" + i;
                String hireDate = "HireDate" + i;
                people[i] = new Faculty(ID, name, address, phoneNumber, email, position, hireDate, "Course" + i, "TeachingTime" + i, "Major" + i);
            }
        }

        for (int i = 0; i < 8; i++) {
            System.out.println(people[i].toString());
        }
    }
}

要在DOS上执行该程序，可以依次执行以下命令：

javac Person.java
javac TestPerson.java
java TestPerson

其中，第一条命令用于编译Person类和其子类的代码，第二条命令用于编译测试程序TestPerson的代码，第三条命令用于运行测试程序。在执行第三条命令时，会输出8个Person对象的信息。