# Annalyns Infiltration

Welcome to Annalyns Infiltration on Exercism's Julia Track.
If you need help running the tests or submitting your code, check out `HELP.md`.
If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)

## Introduction

## Booleans in Julia

True or false values are represented by the `Bool` type.
It contains only two values: `true` and `false`.

```julia-repl
julia> true
true

julia> false
false
```

## Boolean Operators

There are three Boolean operators in Julia.

`&&` is Boolean "and".
It evaluates to `true` if the expressions on *both* sides of `&&` are `true`.

```julia-repl
julia> true && true
true

julia> true && false
false
```

`||` is Boolean "or".
It evaluates to `true` if an expression on *either* side of `||` is `true`.

```julia-repl
julia> true || true
true

julia> false || true
true
```

`!` is Boolean "not".
It exchanges `true` and `false` values.

```julia-repl
julia> !true
false

julia> !false
true
```

For longer and more complicated expressions, it is best to use parentheses to make your intention clear.

```julia-repl
julia> (true || false) && (false && true)
false
```

## Instructions

In this exercise, you'll be writing some logic for a video game a friend is developing.
The game's main character is Annalyn, a brave girl with a fierce and loyal pet dog.
Unfortunately, disaster strikes, as her best friend is kidnapped while searching for berries in the forest.
Annalyn will try to find and free her friend, optionally taking her dog with her on this quest.

Annalyn eventually finds the camp in which her friend is imprisoned and it turns out there are two kidnappers: a mighty knight and a cunning archer.

The player is presented with some options for what to do next.
For each of the four possible options you need to write a function that tells the game whether it should show that option or not.

## 1. Check if the 'Fast Attack' option should be shown

If the knight is sleeping, then Annalyn will be able to make a quick attack into the camp before he can wake up properly and get his armour on.

Implement a function named `can_do_fast_attack` that takes a boolean value which indicates if the knight is awake.
This function returns `true` if the 'Fast Attack' action is available based on the state of the character. Otherwise, returns `false`:

```julia-repl
julia> knight_awake = true

julia> can_do_fast_attack(knight_awake)
false
```

## 2. Check if the 'Spy' option should be shown

The group can be spied upon if at least one of them is awake. Otherwise, spying is a waste of time.

Implement a function named `can_spy` that takes three boolean values, indicating if the knight, archer and prisoner, respectively, are awake.
The function returns `true` if the 'Spy' action is available based on the state of the characters.
Otherwise, returns `false`:

```julia-repl
# Output suppressed from the next 3 lines
julia> knight_awake = false
julia> archer_awake = true
julia> prisoner_awake = false

julia> can_spy(knight_awake, archer_awake, prisoner_awake)
true
```

## 3. Check if the 'Signal Prisoner' option should be shown

The prisoner can be signalled using bird sounds if she is awake and the archer is sleeping.
If the archer is awake then she can't be safely signaled because the archer is also trained in bird signalling.

Implement a function named `can_signal_prisoner` that takes two boolean values, indicating if the archer and prisoner, respectively, are awake.
The function returns `true` if the 'Signal Prisoner' action is available based on the state of the characters.
Otherwise, returns `false`:

```julia-repl
julia> archer_awake = false
julia> prisoner_awake = true

julia> can_signal_prisoner(archer_awake, prisoner_awake)
true
```

## 4. Check if the 'Free Prisoner' option should be shown

Annalyn can try sneaking into the camp to free her friend. This is a risky thing to do and can only succeed in one of two ways:

- If Annalyn has her pet dog with her, she can rescue the prisoner if the archer is asleep.
  The knight is scared of the dog and the archer will not have time to get ready before Annalyn and her friend can escape.

- If Annalyn does not have her dog then she and the prisoner must be very sneaky!
  Annalyn can free the prisoner if she is awake and the knight and archer are both sleeping, but if the prisoner is sleeping, she can't be rescued: she would be startled by Annalyn's sudden appearance and wake up the knight and archer.

Implement a function named `can_free_prisoner` that takes four boolean values.
The first three parameters indicate if the knight, archer and prisoner, respectively, are awake.
The last parameter indicates if Annalyn's pet dog is present.
The function returns `true` if the 'Free Prisoner' action is available based on the state of the characters. Otherwise, it returns `false`:

```julia-repl
julia> knight_awake = false
julia> archer_awake = true
julia> prisoner_awake = false
julia> dog_present = false

julia> can_free_prisoner(knight_awake, archer_awake, prisoner_awake, dog_present)
false
```

## Source

### Created by

- @SaschaMann
- @colinleach

### Contributed to by

- @cmcaine
- @BNAndras