code2

#include <bits/stdc++.h>
using namespace std;

/*
   Comprehensive C++ Example:
   - Classes (OOP)
   - Inheritance
   - STL (vector, map, algorithm)
   - File handling
   - Sorting & searching
*/

class Student {
protected:
    string name;
    int id;
    vector<int> marks;

public:
    Student(string n, int i) : name(n), id(i) {}

    void addMark(int m) {
        marks.push_back(m);
    }

    double getAverage() const {
        if (marks.empty()) return 0.0;
        int sum = accumulate(marks.begin(), marks.end(), 0);
        return (double)sum / marks.size();
    }

    virtual void display() const {
        cout << "ID: " << id << ", Name: " << name;
        cout << ", Avg Marks: " << getAverage() << endl;
    }

    int getId() const { return id; }
};

class GraduateStudent : public Student {
    string thesis;

public:
    GraduateStudent(string n, int i, string t)
        : Student(n, i), thesis(t) {}

    void display() const override {
        Student::display();
        cout << "Thesis: " << thesis << endl;
    }
};

// Utility: search student by ID
Student* findStudent(vector<Student*>& students, int id) {
    for (auto s : students) {
        if (s->getId() == id) return s;
    }
    return nullptr;
}

int main() {
    vector<Student*> students;

    // Create students
    Student* s1 = new Student("Alice", 101);
    s1->addMark(85);
    s1->addMark(90);

    GraduateStudent* s2 = new GraduateStudent("Bob", 102, "AI Research");
    s2->addMark(88);
    s2->addMark(92);

    students.push_back(s1);
    students.push_back(s2);

    // Sort by average marks (descending)
    sort(students.begin(), students.end(), [](Student* a, Student* b) {
        return a->getAverage() > b->getAverage();
    });

    cout << "=== Student List ===" << endl;
    for (auto s : students) {
        s->display();
        cout << "------------------" << endl;
    }

    // Search example
    int searchId = 102;
    Student* found = findStudent(students, searchId);
    if (found) {
        cout << "Found student with ID " << searchId << ":" << endl;
        found->display();
    } else {
        cout << "Student not found." << endl;
    }

    // File output
    ofstream outFile("students.txt");
    for (auto s : students) {
        outFile << s->getId() << " " << endl;
    }
    outFile.close();

    // Cleanup
    for (auto s : students) {
        delete s;
    }

    return 0;
}