diff --git a/CarQueue.java b/CarQueue.java
new file mode 100644
index 0000000..e3380df
--- /dev/null
+++ b/CarQueue.java
@@ -0,0 +1,36 @@
+import java.util.LinkedList;
+import java.util.Queue;
+
+public class CarQueue {
+
+    public static void main(String[] args) {
+        Queue<String> carQueue = new LinkedList<>();
+
+        enqueue(carQueue, "Audi");
+        enqueue(carQueue, "Honda");
+        enqueue(carQueue, "Ford");
+        enqueue(carQueue, "Rolls-Royce");
+
+        printQueueContents(carQueue);
+
+        while (!carQueue.isEmpty()) {
+            String removedCar = dequeue(carQueue);
+            System.out.println(removedCar+" Removed ");
+        }
+
+        if (carQueue.isEmpty()) {
+            System.out.println("The queue is empty.");
+        } else {
+            System.out.println("The queue is not empty.");
+        }
+    }
+    public static void enqueue(Queue<String> queue, String car) {
+        queue.add(car);
+    }
+    public static String dequeue(Queue<String> queue) {
+        return queue.poll();
+    }
+    public static void printQueueContents(Queue<String> queue) {
+        System.out.println("The queue: " + queue);
+    }
+}
\ No newline at end of file
diff --git a/Detective.java b/Detective.java
index 5707416..ea6869a 100644
--- a/Detective.java
+++ b/Detective.java
@@ -1,35 +1,40 @@
- 
-import java.util.ArrayList;
-
-class ToDos {
-    
-  public static void main(String[] args) {
-    
-    // Sherlock
-    ArrayList<String> sherlocksToDos = new ArrayList<String>();
-    
-    sherlocksToDos.add("visit the crime scene");
-    sherlocksToDos.add("play violin");
-    sherlocksToDos.add("interview suspects");
-    sherlocksToDos.add("solve the case");
-    sherlocksToDos.add("apprehend the criminal");
-    
-    // Poirot
-    ArrayList<String> poirotsToDos = new ArrayList<String>();
-    
-    poirotsToDos.add("visit the crime scene");
-    poirotsToDos.add("interview suspects");
-    poirotsToDos.add("let the little grey cells do their work");
-    poirotsToDos.add("trim mustache");
-    poirotsToDos.add("call all suspects together");
-    poirotsToDos.add("reveal the truth of the crime");
-    
-    // Print the size of each ArrayList below:
-
-    
-      
-    // Print the name of the detective with the larger to-do list:
-    
-  }
-  
-}
+import java.util.ArrayList;
+
+class ToDos {
+
+    public static void main(String[] args) {
+
+        // Sherlock
+        ArrayList<String> sherlocksToDos = new ArrayList<String>();
+
+        sherlocksToDos.add("visit the crime scene");
+        sherlocksToDos.add("play violin");
+        sherlocksToDos.add("interview suspects");
+        sherlocksToDos.add("solve the case");
+        sherlocksToDos.add("apprehend the criminal");
+
+        // Poirot
+        ArrayList<String> poirotsToDos = new ArrayList<String>();
+
+        poirotsToDos.add("visit the crime scene");
+        poirotsToDos.add("interview suspects");
+        poirotsToDos.add("let the little grey cells do their work");
+        poirotsToDos.add("trim mustache");
+        poirotsToDos.add("call all suspects together");
+        poirotsToDos.add("reveal the truth of the crime");
+
+        // Print the size of each ArrayList below:
+        System.out.println("Sherlock's to-do list size: " + sherlocksToDos.size());
+        System.out.println("Poirot's to-do list size: " + poirotsToDos.size());
+
+        // Print the name of the detective with the larger to-do list:
+        if (sherlocksToDos.size() > poirotsToDos.size()) {
+            System.out.println("Sherlock Holmes has more tasks.");
+        } else if (sherlocksToDos.size() < poirotsToDos.size()) {
+            System.out.println("Hercules Poirot has more tasks.");
+        } else {
+            System.out.println("Both detectives have the same number of tasks.");
+        }
+    }
+}
+// پوارو کار بیشتری دارد
\ No newline at end of file
diff --git a/HashCollisionChecker.java b/HashCollisionChecker.java
index 80631a7..e555138 100644
--- a/HashCollisionChecker.java
+++ b/HashCollisionChecker.java
@@ -1,29 +1,37 @@
-import java.util.*;
-
-public class HashCollisionChecker {
-    public static <T> int countOfUniqueHashCodes(HashSet<T> set) {
-        // TODO: Implement
-        return 0;
-    }
-
-    public static <K, V> int countOfUniqueHashCodes(HashMap<K, V> map) {
-        // TODO: Implement
-        return 0;
-    }
-
-    public static void main(String[] args) {
-        HashSet<String> set = new HashSet<>();
-        set.add("c#c#c#c#c#c#bBc#c#c#c#bBc#");
-        set.add("abcd");
-        set.add("c#c#c#c#c#c#bBc#c#c#c#c#aa");
-        set.add("1234");
-        set.add("c#c#c#c#c#c#bBc#c#c#c#c#bB");
-        System.out.println(countOfUniqueHashCodes(set)); // 3
-
-        HashMap<String, Integer> map = new HashMap<>();
-        map.put("c#c#c#c#c#c#c#aaaaaaaabBbB", 14);
-        map.put("c#c#c#c#c#c#c#aaaaaaaac#c#", 12);
-        map.put("c#c#c#c#c#c#c#aaaaaaaac#cc", 16);
-        System.out.println(countOfUniqueHashCodes(map)); // 2
-    }
-}
+import java.util.HashMap;
+import java.util.HashSet;
+
+public class HashCollisionChecker {
+
+    public static <T> int countOfUniqueHashCodes(HashSet<T> set) {
+        HashSet<Integer> uniqueHashCodes = new HashSet<>();
+        for (T item : set) {
+            uniqueHashCodes.add(item.hashCode());
+        }
+        return uniqueHashCodes.size();
+    }
+
+    public static <K, V> int countOfUniqueHashCodes(HashMap<K, V> map) {
+        HashSet<Integer> uniqueHashCodes = new HashSet<>();
+        for (K key : map.keySet()) {
+            uniqueHashCodes.add(key.hashCode());
+        }
+        return uniqueHashCodes.size();
+    }
+
+    public static void main(String[] args) {
+        HashSet<String> set = new HashSet<>();
+        set.add("c#c#c#c#c#c#bBc#c#c#c#bBc#");
+        set.add("abcd");
+        set.add("c#c#c#c#c#c#bBc#c#c#c#c#aa");
+        set.add("1234");
+        set.add("c#c#c#c#c#c#bBc#c#c#c#c#bB");
+        System.out.println(countOfUniqueHashCodes(set)); // 3
+
+        HashMap<String, Integer> map = new HashMap<>();
+        map.put("c#c#c#c#c#c#c#aaaaaaaabBbB", 14);
+        map.put("c#c#c#c#c#c#c#aaaaaaaac#c#", 12);
+        map.put("c#c#c#c#c#c#c#aaaaaaaac#cc", 16);
+        System.out.println(countOfUniqueHashCodes(map)); // 2
+    }
+}
\ No newline at end of file
diff --git a/ShuffleLinkedList.java b/ShuffleLinkedList.java
new file mode 100644
index 0000000..5a8791c
--- /dev/null
+++ b/ShuffleLinkedList.java
@@ -0,0 +1,25 @@
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.Scanner;
+
+public class ShuffleLinkedList {
+
+    public static void main(String[] args) {
+        LinkedList<String> list = new LinkedList<>();
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.println("Enter the number of elements in the list:");
+        int numberOfElements = scanner.nextInt();
+        scanner.nextLine();
+
+        System.out.println("Enter the elements :");
+        for (int i = 0; i < numberOfElements; i++) {
+            String element = scanner.nextLine();
+            list.add(element);
+        }
+
+        System.out.println("Original list: " + list);
+        Collections.shuffle(list);
+        System.out.println("Shuffled list: " + list);
+    }
+}
\ No newline at end of file
diff --git a/University.java b/University.java
new file mode 100644
index 0000000..dc71365
--- /dev/null
+++ b/University.java
@@ -0,0 +1,88 @@
+import java.util.*;
+
+class Student implements Comparable<Student> {
+    private String name;
+    private String studentId;
+    private double gpa;
+
+    public Student(String name, String studentId, double gpa) {
+        this.name = name;
+        this.studentId = studentId;
+        this.gpa = gpa;
+    }
+
+    public String getName() {
+        return name;
+    }
+    public String getStudentId() {
+        return studentId;
+    }
+    public double getGpa() {
+        return gpa;
+    }
+
+    @Override
+    public int compareTo(Student other) {
+        return this.studentId.compareTo(other.studentId);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        Student student = (Student) obj;
+        return studentId.equals(student.studentId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(studentId);
+    }
+
+    @Override
+    public String toString() {
+        return "name = " + name +
+                ", studentId = " + studentId +
+                ", gpa = " + gpa ;
+
+    }
+}
+
+public class University {
+
+    public static void main(String[] args) {
+        TreeSet<Student> students = new TreeSet<>();
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.println("Enter the number of students:");
+        int numberOfStudents = scanner.nextInt();
+        scanner.nextLine();
+
+        for (int i = 0; i < numberOfStudents; i++) {
+            System.out.println("Enter Info for student " + (i + 1) + ":");
+            System.out.print("Name: ");
+            String name = scanner.nextLine();
+            System.out.print("Student ID: ");
+            String studentId = scanner.nextLine();
+            System.out.print("GPA: ");
+            double gpa = scanner.nextDouble();
+            scanner.nextLine();
+
+            students.add(new Student(name, studentId, gpa));
+        }
+
+        System.out.print("Enter the Student ID to search for: ");
+        String searchId = scanner.nextLine();
+
+
+        Student searchStudent = new Student("", searchId, 0);
+        Student foundStudent = students.ceiling(searchStudent);
+
+        if (foundStudent != null && foundStudent.getStudentId().equals(searchId)) {
+            System.out.println(foundStudent);
+        } else {
+            System.out.println("Student with ID " + searchId + " not found.");
+        }
+
+    }
+}
\ No newline at end of file