Magician-in-Training

10 Points

arrays

Instructions

As a magician-to-be, Elyse needs to practice some basics. She has a stack of cards that she wants to manipulate.

To make things a bit easier she only uses the cards 1 to 10 so her stack of cards can be represented by an array of numbers. The position of a certain card corresponds to the index in the array. That means position 0 refers to the first card, position 1 to the second card etc.

Note

All functions should update the array of cards and then return the modified array - a common way of working known as the Builder pattern, which allows you to nicely daisy-chain functions together.

1. Retrieve a card from a stack

To pick a card, return the card at index position from the given stack.

Implement the function getCard(at:from:) that takes two arguments: at which is the position of the card in the stack, and from which is the stack of cards. The function should return the card at position index from the given stack.

let index = 2
getCard(at: index, from: [1, 2, 4, 1])
// returns 4

2. Change a card in the stack

Perform some sleight of hand and exchange the card at index position with the replacement card provided.

Implement the function setCard(at:in:to) that takes three arguments: at which is the position of the card in the stack, in which is the stack of cards, and to which is the new card to replace the card at position index. The function should return a copy of the stack with the card at position index replaced with the new card. If the given index is not a valid index in the stack, the original stack should be returned, unchanged.

let index = 2
let newCard = 6
setCard(at: index, in: [1, 2, 4, 1], to: newCard)
// returns [1, 2, 6, 1]

3. Insert a card at the of top the stack

Make a card appear by inserting a new card at the top of the stack.

Implement the function insert(_:atTopOf:) that takes two arguments: the new card to be inserted, and the stack of cards. The function should returns a copy of the stack with the new card provided added to the top of the stack.

let newCard = 8
insert(newCard, atTopOf: [5, 9, 7, 1])
// returns [5, 9, 7, 1, 8]

4. Remove a card from the stack

Make a card disappear by removing the card at the given position from the stack.

Implement the function removeCard(at:from:) that takes two arguments: at which is the position of the card in the stack, and from which is the stack of cards. The function should return a copy of the stack with the card at position index removed. If the given index is not a valid index in the stack, the original stack should be returned, unchanged.

let index = 2
removeCard(at: index, from: [3, 2, 6, 4, 8])
// returns [3, 2, 4, 8]

5. Insert a card in the stack

Make a card appear by inserting a new card at the given position in the stack.

Implement the function insert(_:at:from:) that takes three arguments: the new card to be inserted, the position at which the new card should be inserted, and the stack of cards. The function should return a copy of the stack with the new card provided added at the given position. If the given index is not a valid index in the stack, the original stack should be returned, unchanged.

let newCard = 8
insert(newCard, at: 2, from: [5, 9, 7, 1])
// returns [5, 9, 8, 7, 1]

6. Check size of the stack

Check whether the size of the stack is equal to stackSize or not.

Implement the function checkSizeOfStack(_:_:) that takes two arguments: stack which is the stack of cards, and stackSize which is the size of the stack. The function should return true if the size of the stack is equal to stackSize and false otherwise.

let stackSize = 4
checkSizeOfStack([3, 2, 6, 4, 8], stackSize)
// returns false

swift