Delete Duplicates

• Objective

  • To write methods which remove duplicate elements from an array.

• Purpose

  • To demonstrate practical understanding of arrays, loops, and basic composition.

• Instructions

  • Given an object, IntegerDuplicateDeleter, with a composite Integer[] object, write a method
    • removeDuplicatesExactly which removes all values in the array which occur exactly the specified number of times.
    • removeDuplicates which removes all values in the array which occur at least the specified number of times.
      
      
  • Given an object, StringDuplicateDeleter, with a composite String[] object, write a method
    • removeDuplicatesExactly which removes all values in the array which occur exactly the specified number of times.
    • removeDuplicates which removes all values in the array which occur at least the specified number of times.

• Restrictions

  • No use of any built-in data structures, (Collection, List, Map)
  • Operations should be idempotent
    • If the input is the same, then the outputs of the methods should always be the same, regardless of how many times the method is called.

removeDuplicateExactly(n)

Example 1

• Sample Script

  // : Given
  Integer[] array = new Integer[]{1,1,1,23,23,56,57,58};
  DuplicateDeleter<Integer> deleter = new IntegerDuplicateDeleter(array);
  
  // : When
  Integer[] actual = deleter.removeDuplicateExactly(3);
  
  // : Then
  System.out.println(Arrays.toString(actual));
  

• Sample Output

  [23,23,56,57,58]
  

Example 2

• Sample Script

  // : Given
  Integer[] array = new Integer[]{1,1,1,23,23,56,57,58};
  DuplicateDeleter<Integer> deleter = new IntegerDuplicateDeleter(array);
  
  // : When
  Integer[] actual = deleter.removeDuplicateExactly(1);
  
  // : Then
  System.out.println(Arrays.toString(actual));
  

• Sample Output

  [1,1,1,23,23]
  

Example 3

• Sample Script

  // : Given
  Integer[] array = new Integer[]{0, 0, 0, 1, 1, 2, 3, 3, 3, 4, 4, 5, 5, 5, 5};
  DuplicateDeleter<Integer> deleter = new IntegerDuplicateDeleter(array);
  
  // : When
  Integer[] actual = deleter.removeDuplicateExactly(3);
  
  // : Then
  System.out.println(Arrays.toString(actual));
  

• Sample Output

  [1, 1, 2, 4, 4, 5, 5, 5, 5]
  

removeDuplicates(n)

Example 1

• Sample Script

  // : Given
  Integer[] array = new Integer[]{1,1,1,23,23,56,57,58};
  DuplicateDeleter<Integer> deleter = new IntegerDuplicateDeleter(array);
  
  // : When
  Integer[] actual = deleter.removeDuplicateExactly(1);
  
  // : Then
  System.out.println(Arrays.toString(actual));
  

• Sample Output

  []
  

Example 2

• Sample Script

  // : Given
  Integer[] array = new Integer[]{0, 0, 0, 1, 1, 2, 3, 3, 3, 4, 4, 5, 5, 5, 5};
  DuplicateDeleter<Integer> deleter = new IntegerDuplicateDeleter(array);
  
  // : When
  Integer[] actual = deleter.removeDuplicates(2);
  
  // : Then
  System.out.println(Arrays.toString(actual));
  

• Sample Output

  [2]
  

Example 3

• Sample Script

  // : Given
  Integer[] array = new Integer[]{0, 0, 0, 1, 1, 2, 3, 3, 3, 4, 4, 5, 5, 5, 5};
  DuplicateDeleter<Integer> deleter = new IntegerDuplicateDeleter(array);
  
  // : When
  Integer[] actual = deleter.removeDuplicates(3);
  
  // : Then
  System.out.println(Arrays.toString(actual));
  

• Sample Output

  [1,1,2,4,4]
  

Idempotence

Example 1

• Sample Script

  // : Given
  Integer[] array = new Integer[]{0, 0, 0, 1, 1, 2, 3, 3, 3, 4, 4, 5, 5, 5, 5};
  DuplicateDeleter<Integer> deleter = new IntegerDuplicateDeleter(array);
  deleter.removeDuplicates(0);
  deleter.removeDuplicates(1);
  deleter.removeDuplicates(2);
  
  // : When
  Integer[] actual = deleter.removeDuplicates(3);
  
  // : Then
  System.out.println(Arrays.toString(actual));
  

• Sample Output

  [1,1,2,4,4]
  

Example 2

• Sample Script

  // : Given
  Integer[] array = new Integer[]{1,1,1,23,23,56,57,58};
  DuplicateDeleter<Integer> deleter = new IntegerDuplicateDeleter(array);
  deleter.removeDuplicates(0);
  deleter.removeDuplicates(1);
  deleter.removeDuplicates(2);
  
  // : When
  Integer[] actual = deleter.removeDuplicatesExactly(3);
  
  // : Then
  System.out.println(Arrays.toString(actual));
  

• Sample Output

  [23,23,56,57,58]