模拟毕业生选择指导老师提供的毕业课题老师可增加，删除，修改课题，学生可选择课题,老师和学生都可以查看当前已经选择的结果 以#include<iostream> #include<string>为头文件

好的，这是一个比较复杂的问题，需要设计一些类与函数来实现。以下是一个简单的实现示例：

#include <iostream>
#include <string>
#include <vector>
#include <map>

using namespace std;

class Teacher {
private:
    string name;
    vector<string> topics; // 老师开设的课题列表
public:
    Teacher(string name) {
        this->name = name;
    }
    void addTopic(string topic) {
        topics.push_back(topic);
    }
    void removeTopic(string topic) {
        for (auto it = topics.begin(); it != topics.end(); ++it) {
            if (*it == topic) {
                topics.erase(it);
                break;
            }
        }
    }
    void modifyTopic(string oldTopic, string newTopic) {
        for (auto it = topics.begin(); it != topics.end(); ++it) {
            if (*it == oldTopic) {
                *it = newTopic;
                break;
            }
        }
    }
    string getName() {
        return name;
    }
    vector<string> getTopics() {
        return topics;
    }
};

class Student {
private:
    string name;
    string selectedTopic;
public:
    Student(string name) {
        this->name = name;
    }
    void selectTopic(string topic) {
        selectedTopic = topic;
    }
    string getSelectedTopic() {
        return selectedTopic;
    }
};

class GraduationProject {
private:
    vector<Teacher*> teachers;
    map<string, Student*> students;
public:
    void addTeacher(Teacher* teacher) {
        teachers.push_back(teacher);
    }
    void removeTeacher(Teacher* teacher) {
        for (auto it = teachers.begin(); it != teachers.end(); ++it) {
            if (*it == teacher) {
                teachers.erase(it);
                break;
            }
        }
    }
    void modifyTopic(Teacher* teacher, string oldTopic, string newTopic) {
        teacher->modifyTopic(oldTopic, newTopic);
    }
    void displayAllTopics() {
        for (auto teacher : teachers) {
            cout << "Teacher " << teacher->getName() << " topics:" << endl;
            for (auto topic : teacher->getTopics()) {
                cout << "  " << topic << endl;
            }
        }
    }
    void selectTopic(Student* student, string topic) {
        if (students.find(student->getName()) == students.end()) {
            students[student->getName()] = student;
        }
        students[student->getName()]->selectTopic(topic);
    }
    void displayAllSelections() {
        cout << "Student selections:" << endl;
        for (auto it = students.begin(); it != students.end(); ++it) {
            cout << "  " << it->first << ": " << it->second->getSelectedTopic() << endl;
        }
    }
};

int main() {
    GraduationProject project;
    Teacher *t1 = new Teacher("Tom");
    t1->addTopic("Topic 1");
    t1->addTopic("Topic 2");
    Teacher *t2 = new Teacher("Jerry");
    t2->addTopic("Topic 3");
    t2->addTopic("Topic 4");
    project.addTeacher(t1);
    project.addTeacher(t2);

    Student *s1 = new Student("Alice");
    project.selectTopic(s1, "Topic 2");

    Student *s2 = new Student("Bob");
    project.selectTopic(s2, "Topic 3");

    project.displayAllTopics();
    project.displayAllSelections();

    return 0;
}

这个程序实现了老师添加、删除、修改课题，学生选择课题，以及展示所有老师的课题和所有学生的选择。你可以根据需要进行修改和扩展。