From e47fcf7d73d2d54f265e24b3f85ceaf3ed304020 Mon Sep 17 00:00:00 2001
From: Daan Sieben <daan.sieben@philips.com>
Date: Wed, 3 Apr 2024 11:42:19 +0200
Subject: [PATCH] solutions

---
 exercises/src/bin/exercise_01.rs |  2 +-
 exercises/src/bin/exercise_02.rs |  2 +-
 exercises/src/bin/exercise_03.rs |  2 +-
 exercises/src/bin/exercise_04.rs |  2 +-
 exercises/src/bin/exercise_05.rs |  2 +-
 exercises/src/bin/exercise_06.rs |  5 +++--
 exercises/src/bin/exercise_07.rs | 10 ++++++----
 exercises/src/bin/exercise_08.rs |  2 +-
 exercises/src/bin/exercise_09.rs |  6 +++---
 exercises/src/bin/exercise_10.rs |  2 +-
 exercises/src/bin/exercise_11.rs |  6 +++---
 exercises/src/bin/exercise_12.rs |  2 +-
 exercises/src/bin/exercise_13.rs |  3 ++-
 exercises/src/bin/exercise_14.rs |  5 +++++
 exercises/src/bin/exercise_15.rs |  5 +++++
 exercises/src/bin/exercise_16.rs |  4 ++++
 exercises/src/bin/exercise_17.rs |  3 ++-
 exercises/src/bin/exercise_18.rs | 10 ++++++++--
 exercises/src/bin/exercise_19.rs |  4 +++-
 exercises/src/bin/exercise_20.rs | 13 +++++++++++++
 exercises/src/bin/exercise_21.rs | 11 ++++++++++-
 exercises/src/bin/exercise_22.rs |  5 +++--
 exercises/src/bin/exercise_23.rs |  6 +++++-
 exercises/src/bin/exercise_24.rs | 11 +++++++++++
 exercises/src/bin/exercise_25.rs |  4 ++++
 exercises/src/bin/exercise_26.rs | 16 +++++++++++++---
 exercises/src/bin/exercise_27.rs |  3 ++-
 exercises/src/bin/exercise_28.rs |  9 ++++++---
 exercises/src/bin/exercise_29.rs | 11 ++++++++++-
 exercises/src/bin/exercise_30.rs | 18 +++++++++++++-----
 exercises/src/bin/exercise_31.rs |  4 ++--
 31 files changed, 144 insertions(+), 44 deletions(-)

diff --git a/exercises/src/bin/exercise_01.rs b/exercises/src/bin/exercise_01.rs
index e2bbfca..669fbc6 100644
--- a/exercises/src/bin/exercise_01.rs
+++ b/exercises/src/bin/exercise_01.rs
@@ -4,7 +4,7 @@
 ///
 
 fn exercise() -> i32 {
-    let output = 7;
+    let mut output = 7;
 
     // Do not change below this line __________________________________________
     println!("The value of output is: {}", output);
diff --git a/exercises/src/bin/exercise_02.rs b/exercises/src/bin/exercise_02.rs
index 2a1031f..6ca50bd 100644
--- a/exercises/src/bin/exercise_02.rs
+++ b/exercises/src/bin/exercise_02.rs
@@ -7,7 +7,7 @@ fn exercise() -> i32 {
     let output = 7; // Do not change this line
 
     println!("The value of output is: {}", output);
-    output = 5;
+    let output = 5;
     println!("The value of output is: {}", output);
     output // Do not change this line
 }
diff --git a/exercises/src/bin/exercise_03.rs b/exercises/src/bin/exercise_03.rs
index 89cfb7a..35595f6 100644
--- a/exercises/src/bin/exercise_03.rs
+++ b/exercises/src/bin/exercise_03.rs
@@ -9,7 +9,7 @@ fn exercise() -> i32 {
     let mut output = "seven"; // Do not change this line
 
     println!("The value of output is: {}", output);
-    output = 5;
+    let output = 5;
     println!("The value of output is: {}", output);
     output // Do not change this line
 }
diff --git a/exercises/src/bin/exercise_04.rs b/exercises/src/bin/exercise_04.rs
index c02a788..360c6aa 100644
--- a/exercises/src/bin/exercise_04.rs
+++ b/exercises/src/bin/exercise_04.rs
@@ -9,7 +9,7 @@ fn exercise() -> i32 {
     let mut output = 7; // Do not change this line
     {
         println!("The value of output is: {}", output);
-        output = 5; // <-- how to tell the compiler that this is a different variable?
+        let output = 5; // <-- how to tell the compiler that this is a different variable?
         println!("The value of output is: {}", output);
     }
     output // Do not change this line
diff --git a/exercises/src/bin/exercise_05.rs b/exercises/src/bin/exercise_05.rs
index c9261de..cde93e7 100644
--- a/exercises/src/bin/exercise_05.rs
+++ b/exercises/src/bin/exercise_05.rs
@@ -10,7 +10,7 @@ fn exercise() -> i32 {
 }
 
 fn square(value: i32) -> i32 {
-    value * value;
+    value * value
 }
 
 fn main() {
diff --git a/exercises/src/bin/exercise_06.rs b/exercises/src/bin/exercise_06.rs
index b7ab5da..2add792 100644
--- a/exercises/src/bin/exercise_06.rs
+++ b/exercises/src/bin/exercise_06.rs
@@ -9,12 +9,13 @@ fn exercise() -> i32 {
     divide(value)
 }
 
-fn divide(value: i32) {
+#[allow(clippy::eq_op)]
+fn divide(value: i32) -> i32 {
     if value == 0 {
         0
     } else {
         value / value
-    };
+    }
 }
 
 fn main() {
diff --git a/exercises/src/bin/exercise_07.rs b/exercises/src/bin/exercise_07.rs
index ec40e94..097d111 100644
--- a/exercises/src/bin/exercise_07.rs
+++ b/exercises/src/bin/exercise_07.rs
@@ -12,10 +12,12 @@ fn exercise() -> String {
     let c = String::from("five");
     let d = c;
 
-    // format!("{a}={c}")
-    // format!("{b}={c}")
-    // format!("{a}={d}")
-    // format!("{b}={d}")
+    // format!("{a}={c}") // Invalid: borrow of moved value `c`
+    // format!("{b}={c}") // Invalid: borrow of moved value `c`
+    format!("{a}={d}") // Valid: as a is a primitive type, it has a copy trait,
+                       // meaning that b is not taking ownership but is a copy of a
+                       // format!("{b}={d}") // Valid: as a is a primitive type, it has a copy trait,
+                       // meaning that b is not taking ownership but is a copy of a
 }
 
 fn main() {
diff --git a/exercises/src/bin/exercise_08.rs b/exercises/src/bin/exercise_08.rs
index 926af6f..f2fbbed 100644
--- a/exercises/src/bin/exercise_08.rs
+++ b/exercises/src/bin/exercise_08.rs
@@ -7,7 +7,7 @@
 #[allow(unused)]
 fn exercise() -> String {
     let value = String::from("Hello world");
-    read_string(value);
+    let value = read_string(value);
     value
 }
 
diff --git a/exercises/src/bin/exercise_09.rs b/exercises/src/bin/exercise_09.rs
index 565cd13..8224fff 100644
--- a/exercises/src/bin/exercise_09.rs
+++ b/exercises/src/bin/exercise_09.rs
@@ -9,12 +9,12 @@
 fn exercise() -> String {
     // Do not change this function
     let value = String::from("Hello world");
-    read_string(value);
-    read_string(value);
+    read_string(&value);
+    read_string(&value);
     value
 }
 
-fn read_string(value: String) {
+fn read_string(value: &String) {
     println!("{}", value);
 }
 
diff --git a/exercises/src/bin/exercise_10.rs b/exercises/src/bin/exercise_10.rs
index afeac1f..44827f6 100644
--- a/exercises/src/bin/exercise_10.rs
+++ b/exercises/src/bin/exercise_10.rs
@@ -11,7 +11,7 @@ fn exercise() -> String {
     value
 }
 
-fn read_first_word() {
+fn read_first_word(value: &str) -> &str {
     // Adjust the signature of this function to make the example compile
     value.split_once(' ').unwrap().0
 }
diff --git a/exercises/src/bin/exercise_11.rs b/exercises/src/bin/exercise_11.rs
index 9dd3bad..2dba9f5 100644
--- a/exercises/src/bin/exercise_11.rs
+++ b/exercises/src/bin/exercise_11.rs
@@ -5,12 +5,12 @@
 /// value by 2? Hint: refer to exercise_01 to see how to add mutability to a variable.
 ///
 fn exercise() -> i32 {
-    let value = 5;
-    times_two(value);
+    let mut value = 5;
+    times_two(&mut value);
     value
 }
 
-fn times_two(value: i32) {
+fn times_two(value: &mut i32) {
     *value *= 2; // This line does not require any changes!
 }
 
diff --git a/exercises/src/bin/exercise_12.rs b/exercises/src/bin/exercise_12.rs
index c975f62..9ad8292 100644
--- a/exercises/src/bin/exercise_12.rs
+++ b/exercises/src/bin/exercise_12.rs
@@ -6,7 +6,7 @@
 fn exercise() -> i32 {
     let tuple = (1, 2, 3, 5, 13, 21, 34);
 
-    todo!("return the correct entry from the tuple")
+    tuple.3
 }
 
 fn main() {
diff --git a/exercises/src/bin/exercise_13.rs b/exercises/src/bin/exercise_13.rs
index 8569ce8..75f2ff7 100644
--- a/exercises/src/bin/exercise_13.rs
+++ b/exercises/src/bin/exercise_13.rs
@@ -6,7 +6,8 @@
 ///
 
 fn exercise() -> (i32, String) {
-    todo!("Call get_input and return the sum of all i32 and the concatenation of all Strings")
+    let (a, b, c, d, e) = get_input();
+    (a + c + e, format!("{}{}", b, d))
 }
 
 fn get_input() -> (i32, String, i32, String, i32) {
diff --git a/exercises/src/bin/exercise_14.rs b/exercises/src/bin/exercise_14.rs
index 1024c84..6d01cb6 100644
--- a/exercises/src/bin/exercise_14.rs
+++ b/exercises/src/bin/exercise_14.rs
@@ -18,6 +18,11 @@ struct Order {
     shipping: i32,
     tax: i32,
 }
+impl Order {
+    fn total_cost(&self) -> i32 {
+        self.cost + self.shipping + self.tax
+    }
+}
 
 fn main() {
     exercise();
diff --git a/exercises/src/bin/exercise_15.rs b/exercises/src/bin/exercise_15.rs
index ad67dcb..bc3a832 100644
--- a/exercises/src/bin/exercise_15.rs
+++ b/exercises/src/bin/exercise_15.rs
@@ -26,6 +26,11 @@ struct Order {
     shipping: i32,
     tax: i32,
 }
+impl Order {
+    fn apply_discount_to_cost(&mut self, discount: i32) {
+        self.cost -= discount;
+    }
+}
 
 fn main() {
     exercise();
diff --git a/exercises/src/bin/exercise_16.rs b/exercises/src/bin/exercise_16.rs
index 6186613..bf44a4a 100644
--- a/exercises/src/bin/exercise_16.rs
+++ b/exercises/src/bin/exercise_16.rs
@@ -32,6 +32,10 @@ impl Order {
     fn cost_without_tax(&self) -> i32 {
         self.cost + self.shipping
     }
+
+    fn have_equal_cost_without_tax(order1: &Order, order2: &Order) -> bool {
+        order1.cost_without_tax() == order2.cost_without_tax()
+    }
 }
 
 fn main() {
diff --git a/exercises/src/bin/exercise_17.rs b/exercises/src/bin/exercise_17.rs
index 077face..1810292 100644
--- a/exercises/src/bin/exercise_17.rs
+++ b/exercises/src/bin/exercise_17.rs
@@ -12,7 +12,8 @@ fn exercise() -> i32 {
     let shipping = 10;
     let tax = 5;
 
-    todo!("Create an order using the builder pattern");
+    let order = OrderBuilder::new(cost).shipping(shipping).tax(tax).build();
+    order.total_cost()
 }
 
 #[allow(unused)]
diff --git a/exercises/src/bin/exercise_18.rs b/exercises/src/bin/exercise_18.rs
index 828c44b..dd5aafc 100644
--- a/exercises/src/bin/exercise_18.rs
+++ b/exercises/src/bin/exercise_18.rs
@@ -4,7 +4,7 @@
 /// is positive, -1 if the number is negative, and 0 if the number is zero.
 ///
 
-fn exercise() -> () {
+fn exercise() {
     // Do not change this function
     println!("Sign for 5 is {}", sign(5));
     println!("Sign for 25 is {}", sign(25));
@@ -13,7 +13,13 @@ fn exercise() -> () {
 }
 
 fn sign(value: i32) -> i32 {
-    todo!("implement sign function here")
+    if value > 0 {
+        1
+    } else if value < 0 {
+        -1
+    } else {
+        0
+    }
 }
 
 fn main() {
diff --git a/exercises/src/bin/exercise_19.rs b/exercises/src/bin/exercise_19.rs
index 4a4a954..da1d472 100644
--- a/exercises/src/bin/exercise_19.rs
+++ b/exercises/src/bin/exercise_19.rs
@@ -6,7 +6,9 @@
 fn exercise() -> i32 {
     let mut sum = 0;
 
-    todo!("Sum the numbers from 1 to 100 and store the result in the variable `sum` here");
+    for i in 1..=100 {
+        sum += i;
+    }
 
     sum
 }
diff --git a/exercises/src/bin/exercise_20.rs b/exercises/src/bin/exercise_20.rs
index 3591d62..d4850f4 100644
--- a/exercises/src/bin/exercise_20.rs
+++ b/exercises/src/bin/exercise_20.rs
@@ -17,6 +17,19 @@ enum TrafficLight {
     Yellow,
     Green,
 }
+impl TrafficLight {
+    fn switch_to_next(&self) -> TrafficLight {
+        if self == &TrafficLight::Green {
+            TrafficLight::Yellow
+        } else if self == &TrafficLight::Yellow {
+            TrafficLight::Red
+        } else if self == &TrafficLight::Red {
+            TrafficLight::Green
+        } else {
+            unreachable!()
+        }
+    }
+}
 
 fn main() {
     exercise();
diff --git a/exercises/src/bin/exercise_21.rs b/exercises/src/bin/exercise_21.rs
index 5d2a724..c0ab317 100644
--- a/exercises/src/bin/exercise_21.rs
+++ b/exercises/src/bin/exercise_21.rs
@@ -4,7 +4,7 @@
 /// Try to use pattern matching to implement the method.
 ///
 
-fn exercise() -> () {
+fn exercise() {
     // Do not change this function
     println!("Dog sound: {}", Animal::Dog.make_sound());
     println!("Cat sound: {}", Animal::Cat.make_sound());
@@ -17,6 +17,15 @@ enum Animal {
     Cat,
     Cow,
 }
+impl Animal {
+    fn make_sound(&self) -> &str {
+        match self {
+            Animal::Dog => "Woof",
+            Animal::Cat => "Meow",
+            Animal::Cow => "Moo",
+        }
+    }
+}
 
 fn main() {
     exercise();
diff --git a/exercises/src/bin/exercise_22.rs b/exercises/src/bin/exercise_22.rs
index 9db1bf3..ed47103 100644
--- a/exercises/src/bin/exercise_22.rs
+++ b/exercises/src/bin/exercise_22.rs
@@ -8,8 +8,9 @@ fn exercise() -> i32 {
     let mut sum = 0;
 
     for i in 1..=100 {
-        let divided = integer_divided_by_two(i);
-        todo!("If the `integer_divided_by_two` function returns Some value, add its output to the sum");
+        if let Some(value) = integer_divided_by_two(i) {
+            sum += value;
+        }
     }
 
     sum
diff --git a/exercises/src/bin/exercise_23.rs b/exercises/src/bin/exercise_23.rs
index 8ec1d1f..b05836d 100644
--- a/exercises/src/bin/exercise_23.rs
+++ b/exercises/src/bin/exercise_23.rs
@@ -6,7 +6,11 @@
 use std::num::ParseIntError;
 
 fn exercise(input: &str) -> i32 {
-    todo!();
+    if let Ok(value) = int_value(input) {
+        value
+    } else {
+        0
+    }
 }
 
 #[allow(dead_code)]
diff --git a/exercises/src/bin/exercise_24.rs b/exercises/src/bin/exercise_24.rs
index f80676d..1b145da 100644
--- a/exercises/src/bin/exercise_24.rs
+++ b/exercises/src/bin/exercise_24.rs
@@ -23,6 +23,17 @@ struct Square {
 struct Circle {
     value: f32,
 }
+impl Area for Square {
+    fn area(&self) -> f32 {
+        self.value * self.value
+    }
+}
+impl Area for Circle {
+    fn area(&self) -> f32 {
+        let radius = self.value / 2.0;
+        core::f32::consts::PI * radius * radius
+    }
+}
 
 trait Area {
     fn area(&self) -> f32;
diff --git a/exercises/src/bin/exercise_25.rs b/exercises/src/bin/exercise_25.rs
index 2a589be..55153f2 100644
--- a/exercises/src/bin/exercise_25.rs
+++ b/exercises/src/bin/exercise_25.rs
@@ -21,6 +21,10 @@ fn exercise() -> String {
     )
 }
 
+fn get_first<T>(pair: (T, T)) -> T {
+    pair.0
+}
+
 fn main() {
     println!("{}", exercise());
 }
diff --git a/exercises/src/bin/exercise_26.rs b/exercises/src/bin/exercise_26.rs
index 7c12015..ff0538b 100644
--- a/exercises/src/bin/exercise_26.rs
+++ b/exercises/src/bin/exercise_26.rs
@@ -8,19 +8,29 @@ use std::collections::{HashMap, HashSet};
 
 fn vector_sum(vector: Vec<i32>) -> i32 {
     let mut total = 0;
-    todo!("Return the sum of the vector");
+    for i in vector {
+        total += i;
+    }
     total
 }
 
 fn hashset_product(hashset: HashSet<i32>) -> i32 {
     let mut total = 1;
-    todo!("Return the product of the hashset");
+    for i in hashset {
+        total *= i;
+    }
     total
 }
 
 fn hashmap_sum(hashmap: HashMap<&str, Vec<i32>>) -> HashMap<&str, i32> {
     let mut total = HashMap::new();
-    todo!("Return the sum of the hashmap values per key");
+    for (key, value) in hashmap {
+        let mut sum = 0;
+        for i in value {
+            sum += i;
+        }
+        total.insert(key, sum);
+    }
     total
 }
 
diff --git a/exercises/src/bin/exercise_27.rs b/exercises/src/bin/exercise_27.rs
index baba6ea..b383b49 100644
--- a/exercises/src/bin/exercise_27.rs
+++ b/exercises/src/bin/exercise_27.rs
@@ -6,7 +6,8 @@
 ///
 
 fn exercise(a: i32, b: i32) -> i32 {
-    todo!("Call the apply function twice with a closure defined above");
+    let sum = apply(|a, b| a + b, a, b);
+    apply(|a, b| a * b, sum, b)
 }
 
 fn apply<F: Fn(i32, i32) -> i32>(func: F, a: i32, b: i32) -> i32 {
diff --git a/exercises/src/bin/exercise_28.rs b/exercises/src/bin/exercise_28.rs
index a738775..7cf51cd 100644
--- a/exercises/src/bin/exercise_28.rs
+++ b/exercises/src/bin/exercise_28.rs
@@ -7,15 +7,18 @@ use std::collections::{HashMap, HashSet};
 ///
 
 fn vector_sum(vector: Vec<i32>) -> i32 {
-    todo!("Return the sum of the vector");
+    vector.into_iter().sum()
 }
 
 fn hashset_product(hashset: HashSet<i32>) -> i32 {
-    todo!("Return the product of the hashset");
+    hashset.into_iter().product()
 }
 
 fn hashmap_sum(hashmap: HashMap<&str, Vec<i32>>) -> HashMap<&str, i32> {
-    todo!("Return the sum of the hashmap values per key");
+    hashmap
+        .into_iter()
+        .map(|(key, value)| (key, value.into_iter().sum()))
+        .collect()
 }
 
 fn main() {
diff --git a/exercises/src/bin/exercise_29.rs b/exercises/src/bin/exercise_29.rs
index 89347cc..e42038f 100644
--- a/exercises/src/bin/exercise_29.rs
+++ b/exercises/src/bin/exercise_29.rs
@@ -6,12 +6,21 @@
 fn exercise((orange, apple, banana): (Product, Product, Product)) -> f32 {
     let mut basket = Basket { items: vec![] };
 
-    // basket.add(Product);
+    for _ in 0..3 {
+        basket.add(orange.clone());
+    }
+    for _ in 0..2 {
+        basket.add(apple.clone());
+    }
+    for _ in 0..5 {
+        basket.add(banana.clone());
+    }
 
     basket.print();
     basket.total()
 }
 
+#[derive(Debug, Clone)]
 struct Product {
     #[allow(dead_code)]
     name: String,
diff --git a/exercises/src/bin/exercise_30.rs b/exercises/src/bin/exercise_30.rs
index a6325cf..c6a734c 100644
--- a/exercises/src/bin/exercise_30.rs
+++ b/exercises/src/bin/exercise_30.rs
@@ -6,7 +6,15 @@
 fn exercise((orange, apple, banana): (Product, Product, Product)) -> f32 {
     let mut basket = Basket { items: vec![] };
 
-    // basket.add(Product);
+    for _ in 0..3 {
+        basket.add(&orange);
+    }
+    for _ in 0..2 {
+        basket.add(&apple);
+    }
+    for _ in 0..5 {
+        basket.add(&banana);
+    }
 
     basket.print();
     basket.total()
@@ -20,12 +28,12 @@ struct Product {
     price: f32,
 }
 
-struct Basket {
-    items: Vec<Product>,
+struct Basket<'a> {
+    items: Vec<&'a Product>,
 }
 
-impl Basket {
-    fn add(&mut self, product: Product) {
+impl<'a> Basket<'a> {
+    fn add(&mut self, product: &'a Product) {
         self.items.push(product);
     }
 
diff --git a/exercises/src/bin/exercise_31.rs b/exercises/src/bin/exercise_31.rs
index 4089b6b..581a32d 100644
--- a/exercises/src/bin/exercise_31.rs
+++ b/exercises/src/bin/exercise_31.rs
@@ -17,8 +17,8 @@ mod example {
         Model { value: 5 }
     }
 
-    struct Model {
-        value: i32,
+    pub struct Model {
+        pub value: i32,
     }
 }