19: Add solutions for section "standard_library_types".

Dependencies

• [2] H6XH45OP 0

Change contents

• edit in exercises/standard_library_types/iterators5.rs at line 13
  [2.98174]→[2.98174:98192](∅→∅)
  −

  − // I AM NOT DONE
• edit in exercises/standard_library_types/iterators5.rs at line 36
  [2.98727]

  [2.98727]
  + let out = map.iter().fold(0, |count, val| if val.1 == &value { count + 1 } else { count } );

  + out
• edit in exercises/standard_library_types/iterators5.rs at line 56
  [2.99274]

  [2.99274]
  + let out = collection.iter().fold(0, |count_a, map| count_a + map.iter().fold(0, |count_b, val| if val.1 == &value { count_b + 1 } else { count_b }) );

  + out
• edit in exercises/standard_library_types/iterators4.rs at line 2
  [2.101138]→[2.101138:101156](∅→∅)
  −

  − // I AM NOT DONE
• edit in exercises/standard_library_types/iterators4.rs at line 13
  [2.101502]

  [2.101502]
  + if num == 0 { 0 } else { (1..=num).fold(1, |acc, elem| acc * elem) }
• edit in exercises/standard_library_types/iterators3.rs at line 8
  [2.102219]→[2.102219:102237](∅→∅)
  −

  − // I AM NOT DONE
• replacement in exercises/standard_library_types/iterators3.rs at line 23
  [2.102562]→[2.102562:102625](∅→∅)
  − pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {}
  [2.102562]

  [2.102625]
  + pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {

  + match (a, b) {

  + (_, 0) => Err(DivisionError::DivideByZero),

  + (0, _) => Ok(0),

  + _ => if a % b == 0 {

  + Ok(a / b)

  + } else {

  + Err(DivisionError::NotDivisible(

  + NotDivisibleError {

  + dividend: a,

  + divisor: b

  + }

  + ))

  + }

  + }

  + }
• replacement in exercises/standard_library_types/iterators3.rs at line 42
  [2.102750]→[2.102750:102780](∅→∅)
  − fn result_with_list() -> () {
  [2.102750]

  [2.102780]
  + fn result_with_list() -> Result<Vec<i32>, DivisionError> {
• replacement in exercises/standard_library_types/iterators3.rs at line 44
  [2.102824]→[2.102824:102895](∅→∅)
  − let division_results = numbers.into_iter().map(|n| divide(n, 27));
  [2.102824]

  [2.102895]
  + let division_results = numbers.into_iter().map(|n| divide(n, 27)).collect();

  + division_results
• replacement in exercises/standard_library_types/iterators3.rs at line 50
  [2.103034]→[2.103034:103063](∅→∅)
  − fn list_of_results() -> () {
  [2.103034]

  [2.103063]
  + fn list_of_results() -> Vec<Result<i32, DivisionError>> {
• replacement in exercises/standard_library_types/iterators3.rs at line 52
  [2.103107]→[2.103107:103178](∅→∅)
  − let division_results = numbers.into_iter().map(|n| divide(n, 27));
  [2.103107]

  [2.103178]
  + let division_results = numbers.into_iter().map(|n| divide(n, 27)).collect();

  + division_results
• edit in exercises/standard_library_types/iterators2.rs at line 5
  [2.104347]→[2.104347:104365](∅→∅)
  −

  − // I AM NOT DONE
• replacement in exercises/standard_library_types/iterators2.rs at line 13
  [2.104576]→[2.104576:104604](∅→∅)
  − Some(first) => ???,
  [2.104576]

  [2.104604]
  + Some(first) => first.to_uppercase().to_string() + c.as_str(),
• replacement in exercises/standard_library_types/iterators2.rs at line 22
  [2.104833]→[2.104833:104844](∅→∅)
  − vec![]
  [2.104833]

  [2.104844]
  + let out = words.iter().map(|x| capitalize_first(x)).collect();

  + out
• replacement in exercises/standard_library_types/iterators2.rs at line 31
  [2.105064]→[2.105064:105082](∅→∅)
  − String::new()
  [2.105064]

  [2.105082]
  + // let out = words.iter().fold(String::new(), |acc, elem| acc + &capitalize_first(elem));

  + let out = words.iter().map(|x| capitalize_first(x)).collect();

  + out
• replacement in exercises/standard_library_types/iterators1.rs at line 3
  [2.105719]→[2.105719:105764](∅→∅)
  − // Make me compile by filling in the `???`s
  [2.105719]

  [2.105764]
  + // Make me compile by filling in the `Some(&"")`s
• edit in exercises/standard_library_types/iterators1.rs at line 10
  [2.106053]→[2.106053:106071](∅→∅)
  −

  − // I AM NOT DONE
• replacement in exercises/standard_library_types/iterators1.rs at line 14
  [2.106176]→[2.106176:106236](∅→∅)
  − let mut my_iterable_fav_fruits = ???; // TODO: Step 1
  [2.106176]

  [2.106236]
  + let mut my_iterable_fav_fruits = my_fav_fruits.iter();
• replacement in exercises/standard_library_types/iterators1.rs at line 17
  [2.106301]→[2.106301:106373](∅→∅)
  − assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 2
  [2.106301]

  [2.106373]
  + assert_eq!(my_iterable_fav_fruits.next(), Some(&"custard apple"));
• replacement in exercises/standard_library_types/iterators1.rs at line 19
  [2.106438]→[2.106438:106512](∅→∅)
  − assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 2.1
  [2.106438]

  [2.106512]
  + assert_eq!(my_iterable_fav_fruits.next(), Some(&"peach"));
• replacement in exercises/standard_library_types/iterators1.rs at line 21
  [2.106579]→[2.106579:106651](∅→∅)
  − assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 3
  [2.106579]

  [2.106651]
  + assert_eq!(my_iterable_fav_fruits.next(), None);
• edit in exercises/standard_library_types/box1.rs at line 18
  [2.107589]→[2.107589:107607](∅→∅)
  −

  − // I AM NOT DONE
• replacement in exercises/standard_library_types/box1.rs at line 21
  [2.107652]→[2.107652:107673](∅→∅)
  − Cons(i32, List),
  [2.107652]

  [2.107673]
  + Cons(i32, Box<List>),
• replacement in exercises/standard_library_types/box1.rs at line 34
  [2.107908]→[2.107908:107929](∅→∅)
  − unimplemented!()
  [2.107908]

  [2.107929]
  + List::Nil
• replacement in exercises/standard_library_types/box1.rs at line 38
  [2.107973]→[2.107973:107994](∅→∅)
  − unimplemented!()
  [2.107973]

  [2.107994]
  + List::Cons(0, Box::new(List::Nil))
• edit in exercises/standard_library_types/arc1.rs at line 20
  [2.109282]→[2.109282:109300](∅→∅)
  −

  − // I AM NOT DONE
• replacement in exercises/standard_library_types/arc1.rs at line 27
  [2.109470]→[2.109470:109503](∅→∅)
  − let shared_numbers = // TODO
  [2.109470]

  [2.109503]
  + let shared_numbers = Arc::new(numbers);
• replacement in exercises/standard_library_types/arc1.rs at line 31
  [2.109567]→[2.109567:109603](∅→∅)
  − let child_numbers = // TODO
  [2.109567]

  [2.109603]
  + let child_numbers = shared_numbers.clone();