Double-Null0111: Closures Are Forever
10 Points
capturing
closures
shorthand-arguments
trailing-closures
Instructions
Hello again, Agent Double-Null0111.
The forces of UMBRA are acting up again, and it is up to you to foil their latest scheme. Our intel branch informs us that those Minions are planning to set off a stink-bomb at the Governor's ball.
Since the minions are so clumsy, they often accidentally arm the stink-bombs in their labs and offices. And because they keep forgetting how to disarm their stink-bombs, they have implemented a system generate the disarming instructions that list the order the wires must be cut from the bomb's ID number.
Your job is to write the code that will allow you to disarm the stink-bomb at the ball before it goes off.
1. Write a closure to flip two wires
There are three differently colored wires on each stink-bomb.
Write a closure that takes a (String, String, String) tuple and returns the tuple with the order of the first two elements flipped.
Assign this closure to the name flip.
It is important to note that the type has to be the ChangeClosure (or a sendable type), the type definition is given in the stub file.
Otherwise, the code will not compile.
flip(("red", "yellow", "blue"))
// Returns ("yellow", "red", "blue")2. Write a closure to rotate the wires
Write a closure that takes a (String, String, String) tuple and returns the tuple with the order of the wires rotated to the left.
Assign this closure to the name rotate.
It is important to note that the type has to be the ChangeClosure (or a sendable type), the type definition is given in the stub file.
rotate(("red", "yellow", "blue"))
// Returns ("yellow", "blue", "red")3. Implement a wire shuffle generator
In order to figure out the order in which to cut the stink-bomb wires, you will need to implement a function that generates the proper shuffling function based on the ID number of the stink-bomb.
Implement the function:
makeShuffle(
flipper: @escaping ((String, String, String)) -> (String, String, String),
rotator: @escaping ((String, String, String)) -> (String, String, String)
) -> ([UInt8], (String, String, String)) -> (String, String, String)which takes as input a closure that flips two wires and a closure that rotates the three wires and returns a closure. This returned closure takes the ID number of the stink-bomb and the order of the three wires, and then computes the order the wires need to be cut. The ID number is made of eight bits, and each bit will determine whether to flip or rotate the wires.
For each bit in the ID number, starting with the rightmost bit, you will apply the flipper closure to the wires tuple if the bit is a 0 and you will apply the rotator closure if it is a 1 giving the new state of the wires.
After the appropriate closures have been applied for all eight bits of the ID, the final state of the wires is the order they need to be cut in.
let shuffler = makeShuffle(flipper: flip, rotator: rotate)
// Returns ([UInt8], (String, String, String)) -> (String, String, String)
shuffler([1, 0, 0, 1, 1, 0, 1, 1], ("red", "yellow", "blue"))
// Returns ("red", "blue", "yellow")Double-Null0111: Closures Are Forever
10 Points
capturing
closures
shorthand-arguments
trailing-closures
Instructions
Hello again, Agent Double-Null0111.
The forces of UMBRA are acting up again, and it is up to you to foil their latest scheme. Our intel branch informs us that those Minions are planning to set off a stink-bomb at the Governor's ball.
Since the minions are so clumsy, they often accidentally arm the stink-bombs in their labs and offices. And because they keep forgetting how to disarm their stink-bombs, they have implemented a system generate the disarming instructions that list the order the wires must be cut from the bomb's ID number.
Your job is to write the code that will allow you to disarm the stink-bomb at the ball before it goes off.
1. Write a closure to flip two wires
There are three differently colored wires on each stink-bomb.
Write a closure that takes a (String, String, String) tuple and returns the tuple with the order of the first two elements flipped.
Assign this closure to the name flip.
It is important to note that the type has to be the ChangeClosure (or a sendable type), the type definition is given in the stub file.
Otherwise, the code will not compile.
flip(("red", "yellow", "blue"))
// Returns ("yellow", "red", "blue")2. Write a closure to rotate the wires
Write a closure that takes a (String, String, String) tuple and returns the tuple with the order of the wires rotated to the left.
Assign this closure to the name rotate.
It is important to note that the type has to be the ChangeClosure (or a sendable type), the type definition is given in the stub file.
rotate(("red", "yellow", "blue"))
// Returns ("yellow", "blue", "red")3. Implement a wire shuffle generator
In order to figure out the order in which to cut the stink-bomb wires, you will need to implement a function that generates the proper shuffling function based on the ID number of the stink-bomb.
Implement the function:
makeShuffle(
flipper: @escaping ((String, String, String)) -> (String, String, String),
rotator: @escaping ((String, String, String)) -> (String, String, String)
) -> ([UInt8], (String, String, String)) -> (String, String, String)which takes as input a closure that flips two wires and a closure that rotates the three wires and returns a closure. This returned closure takes the ID number of the stink-bomb and the order of the three wires, and then computes the order the wires need to be cut. The ID number is made of eight bits, and each bit will determine whether to flip or rotate the wires.
For each bit in the ID number, starting with the rightmost bit, you will apply the flipper closure to the wires tuple if the bit is a 0 and you will apply the rotator closure if it is a 1 giving the new state of the wires.
After the appropriate closures have been applied for all eight bits of the ID, the final state of the wires is the order they need to be cut in.
let shuffler = makeShuffle(flipper: flip, rotator: rotate)
// Returns ([UInt8], (String, String, String)) -> (String, String, String)
shuffler([1, 0, 0, 1, 1, 0, 1, 1], ("red", "yellow", "blue"))
// Returns ("red", "blue", "yellow")