Sorting #

This page contains information and coding exercises for sorting, using both Bubble sort and Selection Sort.

Open up the pseudocode compiler in a new tab. You will be using this website to complete the exercises below.

Starter Code #

💻 Copy/paste this starter code into your compiler

//------ Sorting Algorithm -----------------------
NUMS = [15,30,85,25,40,90,50,65,20,60]
output "------Before sorting------"
loop C from 0 to 9
 output NUMS[C]
end loop
output "------Before sorting------"
output
//-----------------------


// YOUR CODE GOES HERE 



//-----------------------
output
output "------After sorting------"
loop C from 0 to 9
 output NUMS[C]
end loop
output "------After sorting------"

Bubble Sort #

💻 Using the example code, write the `bubbleSort`

Using the example code, use the Bubble Sort algorithm to sort the array. If you are unsure how to begin, use the provided checklist to help.

Answer ↕

loop I from 0 to NUMS.length-1
    loop J from 0 to NUMS.length-2
      if NUMS[J]>NUMS[J+1] then
        TEMP = NUMS[J]
        NUMS[J] = NUMS[J+1]
        NUMS[J+1] = TEMP
      end if
    end loop
end loop

Improving your Bubble Sort #

💻 Create a method called `swap()` that can swap two numbers in an array

Parameters: position1, position2, array
Return: updated array

Swap the items at position1 and position2
Return the updated array

Answer ↕

method swap(position1, position2, array)
    TEMP = array[position2]
    array[position2] = array[position1]
    array[position1] = TEMP
    return array
end method

Now use your swap to improve your sorting

💻 Convert your bubble sort code into a method called `bubbleSort`

Parameter: an array of numbers
Return: a sorted array of numbers

Sorts the array
Everytime a swap is required, it should use swap()

Answer ↕

method bubbleSort(ARRAY)
  loop I from 0 to ARRAY.length-1
      loop J from 0 to ARRAY.length-2
        if ARRAY[J]>ARRAY[J+1] then
          ARRAY = swap(J, J+1, ARRAY)
        end if
      end loop
  end loop
  return ARRAY
end method

Selection Sort #

Now you will move on to the next sorting algorithm.

💻 Create a method called `selectionSort`

Parameter: an array of numbers
Return: a sorted array of numbers

Sorts the array
Everytime a swap is required, it should use swap()

You should be able to use the same starter code to test your selectionSort

Answer using swap() ↕

method selectionSort(ARRAY)
  loop I from 0 to ARRAY.length-1
     MIN = ARRAY[I] 
     MIN_INDEX = I
     loop J from I to ARRAY.length-1 
       if ARRAY[J]<MIN then
          MIN = ARRAY[J]
          MIN_INDEX = J
       end if
     end loop
     ARRAY = swap(I, MIN_INDEX, ARRAY)
  end loop
  return ARRAY
end method

Answer without swap() ↕

method selectionSort(ARRAY)
  loop I from 0 to ARRAY.length-1
     MIN = ARRAY[I] 
     MIN_INDEX = I
     loop J from I to ARRAY.length-1 
       if ARRAY[J]<MIN then
          MIN = ARRAY[J]
          MIN_INDEX = J
       end if
     end loop
     TEMP = ARRAY[I]
     ARRAY[I] = ARRAY[MIN_INDEX]
     ARRAY[MIN_INDEX] = TEMP
  end loop
  return ARRAY
end method

Deliverables #

⚡✨
Paste your code in your Exercises lab log

Extensions #

Sort by Alphabetical Order #

💻 Create a helper method that can tell which word should come first alphabetically, and returns true/false. Then adapt one of your sorting algorithms to use this helper method

Sort by Textbook ordering #

Textbooks are ordered in a strange way. The numbers in a textbook chapter might be numbered like this:

[1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.10, 1.11, 1.12, 1.13, 1.14]

💻 Create a helper method that can tell which number is higher and return true/false. Then adapt one of your sorting algorithms to use this helper method.