Practice — Day 1 · Python & Java

Student Marks Manager 📝

LIST DICT EASY ~25 min

📖 Scenario

You are a teacher with a list of students and their marks. Each student is stored as a dictionary with two keys: "name" and "marks". Write a program that automatically calculates the class results.

Starter Code

students = [
    {"name": "Rahul",  "marks": 72},
    {"name": "Priya",  "marks": 85},
    {"name": "Arjun",  "marks": 40},
    {"name": "Sneha",  "marks": 91},
    {"name": "Vikram", "marks": 55},
]

# Write your code below

Your Tasks

Calculate the average marks of the whole class Add up all marks, then divide by number of students
Make a list of students who passed (marks >= 50) Return only their names, not the whole dictionary
Make a list of students who failed (marks < 50) Return only their names
Print the topper's name — student with the highest marks

Expected Output

Average: 68.6
Pass: ['Rahul', 'Priya', 'Sneha', 'Vikram']
Fail: ['Arjun']
Topper: Sneha (91 marks)

💡 One Hint

Use for s in students: to loop. Access each student's marks with s["marks"] and name with s["name"].

Cricket Score Tracker 🏏

TUPLE LIST EASY ~20 min

📖 Scenario

You are building a cricket scorecard app. Each player's score is stored as a tuple — (player_name, runs). Tuples are used because a match score is fixed and should never change after recording.

Starter Code

scores = [
    ("Rohit",   83),
    ("Virat",   45),
    ("Dhoni",   67),
    ("Hardik",  32),
    ("Bumrah",  12),
    ("Shubman", 91),
]
# scores[0] = ("Rohit", 83)
# scores[0][0] = "Rohit",  scores[0][1] = 83

# Write your code below

Your Tasks

Calculate the total runs scored by the whole team
Find the highest scorer — print their name and runs
List all players who scored 50 or more runs Return the full tuples (name, runs) for these players
Calculate the team average (total / number of players)

Expected Output

Total runs: 330
Highest scorer: Shubman - 91 runs
50+ scorers: [('Rohit', 83), ('Dhoni', 67), ('Shubman', 91)]
Team average: 55.0

💡 One Hint

In each tuple, index [0] is the name and index [1] is the runs. You can also unpack like this: for name, runs in scores:

Common Friends Finder 👫

SET EASY ~20 min

📖 Scenario

Think of Instagram's "Mutual Friends" feature. Two people each have a friend list. You need to find who they share, who is exclusive to one person, and the full combined list. Sets are perfect here — they automatically remove duplicates!

Starter Code

rahul_friends = {"Amit", "Priya", "Rohan", "Sneha", "Karan"}
priya_friends = {"Rohan", "Sneha", "Ankit", "Divya"}

# {} with no key:value = SET (not a dictionary!)
# Write your code below

Your Tasks

Find common friends — friends that BOTH have Use the & operator
Find friends that are only Rahul's — Priya doesn't have them Use the - operator
Make a combined list of ALL friends — no duplicates Use the | operator
Print the total count of unique friends

Expected Output

Common: {'Rohan', 'Sneha'}
Only Rahul's: {'Amit', 'Priya', 'Karan'}
All friends: {'Amit', 'Priya', 'Rohan', 'Sneha', 'Karan', 'Ankit', 'Divya'}
Total unique: 7

💡 One Hint

Sets have 3 built-in operators: & = common, - = only left side, | = everything combined. No loops needed!

Phone Book Manager 📱

DICTIONARY EASY ~25 min

📖 Scenario

A phone contact list is basically a dictionary — each name maps to a number. In Python, a dictionary stores key → value pairs. You search by name (key) and instantly get the number (value) — no looping through everything!

Starter Code

phone_book = {
    "Rahul":  "9876543210",
    "Priya":  "9123456789",
    "Arjun":  "9988776655",
}

# Write your code below — complete each task one by one

Your Tasks

Add a new contact: "Sneha" → "9001122334"
Search for "Priya" — print her number if she exists Check if she exists before accessing, to avoid errors
Delete "Arjun" from the phone book
Print all contacts in alphabetical order
Search for "Virat" — if not found, print "Contact not found!" without crashing There is a safe dictionary method for this!

Expected Output

Sneha added!
Priya's number: 9123456789
Arjun deleted!
All contacts: Priya | Rahul | Sneha
Searching Virat... Contact not found!

💡 One Hint

For Task 5, using phone_book["Virat"] will crash if Virat doesn't exist. Use phone_book.get("Virat", "Contact not found!") instead — it returns the default value safely.

Simple Student Class 🎓

OOP EASY ~30 min

📖 Scenario

Instead of writing separate code for each student, create a Class — a blueprint. Then create individual student objects from it. A Topper subclass inherits everything from Student and adds scholarship logic. This is the core idea of OOP!

Starter Code

class Student:
    def __init__(self, name, roll_no, marks):
        pass   # store name, roll_no, marks using self

    def get_grade(self):
        pass   # return 'A', 'B', or 'C'

    def display(self):
        pass   # print name, roll no, marks, grade


class Topper(Student):
    def __init__(self, name, roll_no, marks):
        pass   # call super().__init__ here

    def get_scholarship(self):
        pass   # return scholarship amount

Your Tasks

Fill __init__ — store name, roll_no, marks using self
Fill get_grade() — return "A" if marks>=80, "B" if marks>=60, else "C"
Fill display() — print all info neatly, call self.get_grade() inside it
Fill Topper.__init__ — call super().__init__() so it inherits from Student
Fill get_scholarship() — "₹10,000" if marks>=90, else "No scholarship"

Expected Output

💡 One Hint

Every method in a class needs self as its first parameter. self.name = name saves the value to the object. In Topper, don't forget super().__init__(name, roll_no, marks) — otherwise name/marks won't be set!

Student Marks Manager 📝

ARRAYLIST HASHMAP EASY ~25 min

📖 Scenario

You are a teacher with a list of students and their marks. Each student's data is stored in a String[] array (name at index 0, marks at index 1). Use an ArrayList to hold all students. Write a program that automatically calculates class results.

Starter Code

import java.util.*;

public class MarksManager {
    public static void main(String[] args) {

        ArrayList<String[]> students = new ArrayList<>();
        students.add(new String[]{"Rahul",  "72"});
        students.add(new String[]{"Priya",  "85"});
        students.add(new String[]{"Arjun",  "40"});
        students.add(new String[]{"Sneha",  "91"});
        students.add(new String[]{"Vikram", "55"});

        // Write your code below
    }
}

Your Tasks

Calculate the average marks of the whole class Use Integer.parseInt(s[1]) to convert String marks to int
Make a list of students who passed (marks >= 50) Print only their names using s[0]
Make a list of students who failed (marks < 50) Print only their names
Print the topper's name — student with the highest marks

Expected Output

Average: 68.6
Pass: [Rahul, Priya, Sneha, Vikram]
Fail: [Arjun]
Topper: Sneha (91 marks)

💡 One Hint

Loop with for (String[] s : students). Access name via s[0] and marks via Integer.parseInt(s[1]). For average, cast to double: (double) total / students.size().

Cricket Score Tracker 🏏

2D ARRAY ARRAYLIST EASY ~20 min

📖 Scenario

You are building a cricket scorecard app. Each player's score is stored as a String[] with 2 elements — {name, runs}. Since match scores are fixed after recording, we use a simple array per player and store them all in one list.

Starter Code

import java.util.*;

public class CricketTracker {
    public static void main(String[] args) {

        String[][] scores = {
            {"Rohit",   "83"},
            {"Virat",   "45"},
            {"Dhoni",   "67"},
            {"Hardik",  "32"},
            {"Bumrah",  "12"},
            {"Shubman", "91"},
        };
        // scores[0][0] = "Rohit",  scores[0][1] = "83"

        // Write your code below
    }
}

Your Tasks

Calculate the total runs scored by the whole team
Find the highest scorer — print their name and runs
List all players who scored 50 or more runs Print name and runs for each qualifying player
Calculate the team average (total / number of players)

Expected Output

Total runs: 330
Highest scorer: Shubman - 91 runs
50+ scorers: Rohit(83), Dhoni(67), Shubman(91)
Team average: 55.0

💡 One Hint

Loop with for (String[] p : scores). Use p[0] for name and Integer.parseInt(p[1]) for runs. Track the max using a variable that you update inside the loop.

Common Friends Finder 👫

HASHSET EASY ~20 min

📖 Scenario

Think of Instagram's "Mutual Friends" feature. Two people each have a friend list. Use Java's HashSet — it automatically removes duplicates and has built-in methods for intersection, difference, and union operations.

Starter Code

import java.util.*;

public class FriendFinder {
    public static void main(String[] args) {

        HashSet<String> rahulFriends = new HashSet<>(
            Arrays.asList("Amit", "Priya", "Rohan", "Sneha", "Karan")
        );
        HashSet<String> priyaFriends = new HashSet<>(
            Arrays.asList("Rohan", "Sneha", "Ankit", "Divya")
        );

        // Write your code below
    }
}

Your Tasks

Find common friends — friends that BOTH have Create a copy and use .retainAll() method
Find friends that are only Rahul's — Priya doesn't have them Create a copy and use .removeAll() method
Make a combined list of ALL friends — no duplicates Create a copy and use .addAll() method
Print the total count of unique friends

Expected Output

Common: [Rohan, Sneha]
Only Rahul's: [Amit, Priya, Karan]
All friends: [Amit, Priya, Rohan, Sneha, Karan, Ankit, Divya]
Total unique: 7

💡 One Hint

Always work on a copy — new HashSet<>(rahulFriends) — so the original set isn't modified. Then call copy.retainAll(priyaFriends) to keep only common elements.

Phone Book Manager 📱

HASHMAP TREEMAP EASY ~25 min

📖 Scenario

A phone contact list is a classic HashMap in Java — each name (key) maps to a number (value). Use TreeMap when you need contacts in sorted/alphabetical order, since HashMap doesn't guarantee any order.

Starter Code

import java.util.*;

public class PhoneBook {
    public static void main(String[] args) {

        HashMap<String, String> phoneBook = new HashMap<>();
        phoneBook.put("Rahul", "9876543210");
        phoneBook.put("Priya", "9123456789");
        phoneBook.put("Arjun", "9988776655");

        // Write your code below — complete each task one by one
    }
}

Your Tasks

Add a new contact: "Sneha" → "9001122334"
Search for "Priya" — print her number if she exists Use .containsKey() before accessing to avoid errors
Delete "Arjun" from the phone book using .remove()
Print all contacts in alphabetical order Hint: use a TreeMap for automatic sorting
Search for "Virat" — if not found, print "Contact not found!" without crashing Use .getOrDefault() for safe lookup

Expected Output

Sneha added!
Priya's number: 9123456789
Arjun deleted!
All contacts: Priya | Rahul | Sneha
Searching Virat... Contact not found!

💡 One Hint

Use phoneBook.getOrDefault("Virat", "Contact not found!") — it returns the value if key exists, otherwise returns your default string safely without throwing an exception.

Simple Student Class 🎓

OOP INHERITANCE EASY ~30 min

📖 Scenario

Instead of writing separate code for each student, create a Class — a blueprint. Then create individual student objects from it. A Topper subclass extends Student and adds scholarship logic using Java's extends keyword and super() constructor call.

Starter Code

class Student {
    String name;
    int rollNo, marks;

    Student(String name, int rollNo, int marks) {
        // TODO: assign to this.name, this.rollNo, this.marks
    }

    String getGrade() {
        // TODO: return "A" / "B" / "C"
        return "";
    }

    void display() {
        // TODO: print name | rollNo | marks | grade
    }
}

class Topper extends Student {

    Topper(String name, int rollNo, int marks) {
        super(name, rollNo, marks); // calls Student's constructor
    }

    String getScholarship() {
        // TODO: return "₹10,000" or "No scholarship"
        return "";
    }
}

public class Main {
    public static void main(String[] args) {
        Student s1 = new Student("Rahul", 101, 75);
        s1.display();

        Topper t1 = new Topper("Sneha", 102, 95);
        t1.display();
        System.out.println(t1.getScholarship());
    }
}

Your Tasks

Fill the Student constructor — assign this.name = name, etc.
Fill getGrade() — return "A" if marks>=80, "B" if marks>=60, else "C"
Fill display() — print all info neatly, call getGrade() inside it
The super() in Topper is already there — understand why it's needed
Fill getScholarship() — return "₹10,000" if marks>=90, else "No scholarship"

Expected Output

💡 One Hint

In Java, use this.name = name inside the constructor to distinguish the field from the parameter. In getGrade(), use if-else if-else with this.marks. The super() call in Topper must be the first line of the constructor!

5 Questions — Try It Yourself 💪