Code Ideas

Tools

Library Index

Make a collection of your favourite books.

• Sort them by author, series, IBAN etc.
• Group and sort by meta data (e.g. order of books in a series)

Games

Guess a number

• The program generates a number between 1 and 10
• User inputs a number
• The program tells the user if their number is greater, smaller or equal to the generated number
• If the user's number equals the programs number, the game is over

Extra 1: When the user guesses correctly, the program tells them how many tries they needed to do so

Extra 2: When the user guesses correctly, they can start a new round

Tic Tac Toe

• Render a Tic Tac Toe board
• Ask players to enter coordinates to place their game piece
• Check if placement is valid
• Check if anyone has won

  |---|---|---|
A | X |   | O |
  |---|---|---|
B |   | O |   |
  |---|---|---|
C | O | X |   |
  |---|---|---|
    1   2   3

Hint 1

Use a single list to represent the game board.

Hint 2

Use two nested for-loops to render the game board (x- and y-coordinates).

Hint 3

You can map the index of a list to 2-dimensional coordinates by splitting it into four components:

• Width ($w$)
• Height ($h$)
• X-coordinate ($x$)
• Y-coordinate ($y$)

So the calculation of a cell is:

$f(x,y) = y \times w + x$

Solution

The gameboard has a size of 3x3 cells so the size of the list / array is $x \times y = 9$.

gameboard = ["", "", "", "", "", "", "", "", ""]

To represent a game piece, set the appropriate index to "O" or "X". The list index of $x$- and $y$-coordinates can be calculated with $y \times W + x$ where $W$ is the width of the game board.

gameboard[y * 3 + x] = "O"

Use a function with the signature putPiece(type: string, x: int, y: int): boolean to do this.

Inside this function, check if cell is already occupied or invalid. Return false for errors and show a message to the player.

function putPiece(type: string, x: int, y: int): boolean {
  if (x < 0 || x > 2) return false
  if (gameboard[y * 3 + x] != "") return false
  gameboard[y * 3 + x] = "O"
  return true
}

Render the game board with two nested for-loops.

for (y = 0; y < 3; y++) {
  for (x = 0; x < 3; x++) {
    write(gameboard[y * 3 + x]) // write current x-coordinate
  }
  write("\n") // write a newline before y-coordinate change
}

Use a function to check neighbors of a game piece.

function checkWin(player: string): boolean { // Takes "O" or "X" and returns true if player has won
  // Check horizontal lines
  for (x = 0; x < 3; x++) {
    if (gameboard[x] == player && gameboard[3 + x] == player && gameboard[6 + x] == player) return true
  }

  // Check vertical lines
  for (y = 0; y < 3; y++) {
    if (gameboard[y * 3] == player && gameboard[y * 3 + 1] == player && gameboard[y * 3 + 2] == player) return true
  }

  // Check diagonals
  if (gameboard[0] == player && gameboard[4] == player && gameboard[8] == player) return true
  if (gameboard[2] == player && gameboard[4] == player && gameboard[6] == player) return true
}

Additional ideas

• Render the game board with box-drawing characters
• Make the game board bigger
• Add more pieces in one line needed to win (e.g. four in a row)
• Highlight the winning row with color or formatting
• Add a high-score list