Added Exercise E7

exercises/standard_exercises/E7.md

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+# Java Collections - Practice Exercises
+_Disclaimer_: The following exercises have been created using AI Tools, they are based on information from lecture 7 of the course "Programmering för testare" at ITHS. 
+
+## Warm-up Exercise 🌅
+Before diving into collections, let's warm up our programming skills! 
+
+Create a simple array of integers with the values 1, 2, 3, 4, 5. Write code to:
+1. Print all numbers
+2. Print the sum of all numbers
+3. Print all numbers in reverse order
+
+This will help you remember array basics before we move to collections! 
+
+## "Easy" Exercises 🌱
+
+### B1: List Basics
+Create an `ArrayList<String>` that contains your favorite colors. Write code to:
+- Add at least 3 colors
+- Print all colors
+- Check if "blue" exists in your list
+- Remove one color and print the updated list
+
+### B2: Set Introduction
+Create a `HashSet<Integer>` and demonstrate how it handles duplicates:
+- Add the numbers: 1, 2, 2, 3, 3, 3
+- Print the set
+- Print the size of the set
+- Try to explain why the size is what it is
+
+### B3: Queue Practice
+Create a `Queue<String>` representing people waiting in line at a coffee shop:
+- Add at least 3 people to the queue
+- Print who is first in line
+- Serve (remove) the first person
+- Add another person to the queue
+- Print the entire queue
+
+## Intermediate Exercises 🌿
+
+### I1: List Operations
+Create an `ArrayList<Integer>` with numbers 1-10. Write methods to:
+- Remove all even numbers
+- Double all remaining numbers
+- Calculate the average of the remaining numbers
+- Print the final list and the average
+
+### I2: Set Comparison
+Create two `HashSet<String>` objects containing names of fruits:
+- Set 1: "apple", "banana", "orange", "mango"
+- Set 2: "apple", "mango", "grape", "pear"
+Write code to find:
+- Which fruits are in both sets?
+- Which fruits are unique to Set 1?
+- Which fruits are unique to Set 2?
+
+### I3: Map Usage
+Create a `HashMap<String, Integer>` to store student names and their scores:
+- Add at least 5 student-score pairs
+- Print all students who scored above 90
+- Find and print the student with the highest score
+- Calculate the average score of all students
+
+## Hard Exercises 🌳
+
+### H1: List Manipulation
+Create an `ArrayList<Integer>` with 20 random numbers between 1-100.
+Write methods to:
+- Sort the list in ascending order without using Collections.sort()
+- Remove all numbers that appear more than once
+- Find the second-highest number
+- Calculate the median value
+
+### H2: Custom Object Collections
+Create a class `Book` with properties:
+- title (String)
+- author (String)
+- year (int)
+- isbn (String)
+
+Then create a `HashSet<Book>` and:
+- Add several books (including some duplicates with same ISBN)
+- Override equals() and hashCode() to prevent duplicate ISBNs
+- Create a method to find all books by a specific author
+- Sort the books by year using a TreeSet
+
+### H3: Advanced Map Operations
+Create a `HashMap<String, List<Integer>>` to store student names and their test scores throughout the year:
+- Add at least 3 students with 4 test scores each
+- Calculate each student's average score
+- Find the student with the most improved scores (biggest difference between first and last test)
+- Create a method to get all students whose average is above a given threshold
+
+## Challenge Exercises 🏆
+
+### C1: Library Management System
+Create a simple library management system using various collections:
+- Use a `Map<String, Book>` to store books by ISBN
+- Use a `Set<String>` to store member IDs
+- Use a `Map<String, List<String>>` to track which books are borrowed by which members
+- Implement methods for:
+  * Adding new books
+  * Registering new members
+  * Borrowing books
+  * Returning books
+  * Listing all books borrowed by a member
+  * Finding most popular books (most times borrowed)
+
+### C2: Tournament Bracket Generator
+Create a tournament bracket system using various collections:
+- Use a `Queue<String>` for participants waiting to play
+- Use a `Map<String, Integer>` to store player scores
+- Use a `List<List<String>>` to represent tournament rounds
+- Implement methods for:
+  * Adding participants
+  * Generating random matches
+  * Recording match results
+  * Advancing winners to next round
+  * Displaying current tournament status
+  * Determining tournament winner
+
+## Tips for All Exercises 💡
+- Start with simpler tasks and gradually move to more complex ones
+- Test your code with different inputs
+- Consider edge cases (empty collections, null values, etc.)
+- Use appropriate exception handling where needed
+- Document your code with comments
+- Try to make your code as clean and readable as possible
+
+## Need Help? 🤔
+Remember these resources:
+- Java Documentation for Collections
+- Your lecture notes
+- Draw diagrams if you're stuck
+- Break down complex problems into smaller steps
+- Ask for help after trying to solve it yourself first
+
+Good luck with your exercises! Remember, practice makes perfect! 🚀