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  1. import java.util.ArrayList;
  2. import java.util.LinkedHashSet;
  3.  
  4. /**
  5.  * The Sequence class represents a collection of integers stored in an ArrayList.
  6.  * It provides methods to add numbers, remove duplicate values, and display the sequence.
  7.  */
  8. class Sequence {
  9.     private ArrayList<Integer> numbers; // List to store the sequence of numbers
  10.  
  11.     /**
  12.      * Constructor to initialize an empty sequence.
  13.      */
  14.     public Sequence() {
  15.         numbers = new ArrayList<>();
  16.     }
  17.  
  18.     /**
  19.      * Adds a number to the sequence.
  20.      *
  21.      * @param num The integer to be added to the sequence.
  22.      */
  23.     public void add(int num) {
  24.         numbers.add(num);
  25.     }
  26.  
  27.     /**
  28.      * Removes duplicate values from the sequence while keeping only the first occurrence.
  29.      * The original sequence is modified in place.
  30.      *
  31.      * This method does not return anything, but it updates the sequence.
  32.      */
  33.     public void removeDuplicates() {
  34. // Using LinkedHashSet to remove duplicates while maintaining insertion order
  35.         LinkedHashSet<Integer> uniqueNumbers = new LinkedHashSet<>(numbers);
  36.         numbers.clear(); // Clear the original list
  37.         numbers.addAll(uniqueNumbers); // Add back the unique numbers
  38.     }
  39.  
  40.     /**
  41.      * Prints the sequence to the console.
  42.      * This method does not return anything.
  43.      */
  44.     public void printSequence() {
  45.         System.out.println(numbers);
  46.     }
  47. }
  48.  
  49. /**
  50.  * The SequenceTester class tests the functionality of the Sequence class.
  51.  * It creates multiple sequences, adds numbers, removes duplicates, and displays results.
  52.  */
  53. class SequenceTester {
  54.     public static void main(String[] args) {
  55. // Creating first sequence
  56.         Sequence seq1 = new Sequence();
  57.         seq1.add(1);
  58.         seq1.add(4);
  59.         seq1.add(9);
  60.         seq1.add(16);
  61.         seq1.add(9);
  62.         seq1.add(7);
  63.         seq1.add(4);
  64.         seq1.add(9);
  65.         seq1.add(11);
  66.  
  67. // Display original sequence
  68.         System.out.println("Original Sequence 1:");
  69.         seq1.printSequence();
  70.  
  71. // Remove duplicates and display updated sequence
  72.         seq1.removeDuplicates();
  73.         System.out.println("After removing duplicates:");
  74.         seq1.printSequence();
  75.  
  76. // Creating second sequence
  77.         Sequence seq2 = new Sequence();
  78.         seq2.add(3);
  79.         seq2.add(3);
  80.         seq2.add(3);
  81.         seq2.add(5);
  82.         seq2.add(7);
  83.         seq2.add(7);
  84.  
  85.         System.out.println("\nOriginal Sequence 2:");
  86.         seq2.printSequence();
  87.  
  88.         seq2.removeDuplicates();
  89.         System.out.println("After removing duplicates:");
  90.         seq2.printSequence();
  91.  
  92. // Creating third sequence
  93.         Sequence seq3 = new Sequence();
  94.         seq3.add(10);
  95.         seq3.add(20);
  96.         seq3.add(30);
  97.         seq3.add(20);
  98.         seq3.add(10);
  99.  
  100.         System.out.println("\nOriginal Sequence 3:");
  101.         seq3.printSequence();
  102.  
  103.         seq3.removeDuplicates();
  104.         System.out.println("After removing duplicates:");
  105.         seq3.printSequence();
  106.     }
  107. }
Success #stdin #stdout 0.1s 52744KB
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stdin
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Standard input is empty
stdout
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Original Sequence 1:
[1, 4, 9, 16, 9, 7, 4, 9, 11]
After removing duplicates:
[1, 4, 9, 16, 7, 11]

Original Sequence 2:
[3, 3, 3, 5, 7, 7]
After removing duplicates:
[3, 5, 7]

Original Sequence 3:
[10, 20, 30, 20, 10]
After removing duplicates:
[10, 20, 30]
https://ideone.com/mLXakA
language:
Java (HotSpot 12)
created:
3 days ago
visibility:
public

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