Chapter 3: Excercises

This page contains a set of excercises for the corresponding chapter.
Read the task description, copy the code template if present and solve it in your Eclipse.
If you are stuck, you can show the solution for this task. Be careful not to spoil the solution for yourself unnecessarily.

Contents

1. Shopping List
2. Filter List
3. Sort List
4. Chessboard

Shopping List

This task is the expansion of the shopping list example from chapter 3.

1. Declare a composition Item which can store the name of the item and its price.
2. Initialize three items: item1{bread, 1.99}, item2{beer, 14.99}, item3{ham, 3.99}.
   Put all of these items into a single list and print the list on the console.
3. Iterate over the list and compute the total price.
4. Create a cheaperList, iterate over the normal list and append items with the price of under 10.0 to the cheaper list.

The output of the program should look like this:

Shopping list: [Item{name = bread, price = 1.99}, Item{name = beer, price = 14.99}, Item{name = ham, price = 3.99}] Total price: 20.97 Cheaper list: [Item{name = bread, price = 1.99}, Item{name = ham, price = 3.99}]

Show solution

program shoppingList import Strings import IO import Lists type Item : composition attribute name : string attribute price : rational endtype main variable item1 : Item variable item2 : Item variable item3 : Item item1.name := "bread" item1.price := 1.99 item2.name := "beer" item2.price := 14.99 item3.name := "ham" item3.price := 3.99 variable shoppingList : list<Item> shoppingList := [item1, item2, item3] IO.writeString("Shopping list: " & Strings.genericToString(shoppingList)) IO.writeLine() variable totalPrice : rational variable i : integer loop if i >= Lists.lengthOf(shoppingList) then exit endif totalPrice := totalPrice + shoppingList[i].price i := i + 1 endloop IO.writeString("Total price: ") IO.writeRational(totalPrice) IO.writeLine() variable cheaperList : list<Item> i := 0 loop if i >= Lists.lengthOf(shoppingList) then exit endif if(shoppingList[i].price < 10.00) then cheaperList := Lists.append(cheaperList, shoppingList[i]) endif i := i + 1 endloop IO.writeString("Cheaper list: " & Strings.genericToString(cheaperList)) IO.writeLine() endmain

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Filter List

Your are given a list with 10 random generated numbers between 0 and 10.
Your task is to filter odd numbers out of this list and print the filtered list.

The result could look like that:

[6, 2, 6, 2, 9, 4, 7, 8, 2, 3] [6, 2, 6, 2, 4, 8, 2]

Hint: you can use removePosition to remove odd numbers or append even numbers to a temporary list.

program filterList import IO import Lists import Mathematics import Strings main variable lst : list<integer> variable length : integer length := 10 variable i : integer loop if i = length then exit endif i := i + 1 lst := Lists.append(lst, Mathematics.randomInteger(0, 10)) endloop IO.writeString(Strings.genericToString(lst) & "\n") // IMPLEMENT YOU SOLUTION HERE // END OF THE IMPLEMENTATION endmain

Show solution

program filterList import IO import Lists import Mathematics import Strings main variable liste : list<integer> variable laenge : integer laenge := 10 variable i : integer loop if i = laenge then exit endif i := i + 1 liste := Lists.append(liste, Mathematics.randomInteger(0, 10)) endloop IO.writeString(Strings.genericToString(liste) & "\n") i := 0 loop if (liste[i] mod 2) = 1 then liste := Lists.removePosition(liste, i) else i := i + 1 endif if i = Lists.lengthOf(liste) then exit endif endloop IO.writeString(Strings.genericToString(liste) & "\n") endmain

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Sort List

Your are given a list with 10 random generated numbers between 0 and 10.
Your task is tothis list in ascending order and print the result.

The result could look like that:

[0, 2, 10, 4, 8, 9, 8, 9, 10, 9] [0, 2, 4, 8, 8, 9, 9, 9, 10, 10]

Hint: you can compare pairs of neighbouring values and swap them if necessary (google: bubblesort).
Alternatively, you can remove the smallest number from the original list and append it to a temporary list until the original list is empty.

program sortList import IO import Lists import Mathematics import Strings main variable lst : list<integer> variable length : integer length := 10 variable i : integer loop if i = length then exit endif i := i + 1 lst := Lists.append(lst, Mathematics.randomInteger(0, 10)) endloop IO.writeString(Strings.genericToString(lst) & "\n") // IMPLEMENT YOU SOLUTION HERE // END OF THE IMPLEMENTATION endmain

Show solution

program sortList import IO import Lists import Mathematics import Strings main variable liste : list<integer> variable laenge : integer laenge := 10 variable i : integer loop if i = laenge then exit endif i := i + 1 liste := Lists.append(liste, Mathematics.randomInteger(0, 10)) endloop IO.writeString(Strings.genericToString(liste) & "\n") i := 0 loop if i = laenge - 1 then exit endif variable j : integer loop if j = laenge - 1 then exit endif if liste[j] > liste[j + 1] then variable temp : integer temp := liste[j] liste[j] := liste[j+1] liste[j+1] := temp endif j := j + 1 endloop i := i + 1 endloop IO.writeString(Strings.genericToString(liste) & "\n") endmain

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Chessboard

This task is the expansion of the chessboard example from chapter 3.

1. Declare an enueration PieceType with value literals: PAWN, ROOK, KNIGHT, BISHOP, QUEEN, KING.
2. Declare an enueration Color with value literals: BLACK, WHITE.
3. Declare a composition Piece which has a pieceType and a color.
4. Declare a composition Field which has a color, a number, a character and a piece.
5. In the main procedure, declare a chessboard as a two dimensional list of Fields.
   Initialize it as [8 ** [8 ** Field{}]].
6. Iterate of this list, set the corresponding number and character coordinates as well as the correct color of each field.
7. Print your chessboard on the console.

The resulting output should look like in the image below.
As you can see, a pawn is placed on every field, since it is a default value in this case.
We will solve this issue in chapter 5.


Show solution

program chessboardTask import Lists import IO import Strings type PieceType : enumeration PAWN, ROOK, KNIGHT, BISHOP, QUEEN, KING endtype type Color : enumeration BLACK, WHITE endtype type Piece : composition attribute pieceType : PieceType attribute color : Color endtype type Field : composition attribute color : Color attribute number : integer attribute character : string attribute piece : Piece endtype main variable chessboard : list<list<Field>> chessboard := [8 ** [8 ** Field{}]] variable abc : list<string> abc := ["a", "b", "c", "d", "e", "f", "g", "h"] variable i : integer loop if i = Lists.lengthOf(chessboard) then exit endif variable j : integer loop if j = Lists.lengthOf(chessboard) then exit endif chessboard[i][j].number := 8-i chessboard[i][j].character := abc[j] if (i + j) mod 2 = 1 then chessboard[i][j].color := Color.BLACK else chessboard[i][j].color := Color.WHITE endif j := j + 1 endloop i := i + 1 endloop i := 0 loop if i = Lists.lengthOf(chessboard) then exit endif IO.writeString(Strings.genericToString(chessboard[i]) & "\n") i := i + 1 endloop endmain

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