Add collections solutions

exercises/collections/hashmap1.rs

@@ -11,17 +11,16 @@
 // Execute the command `rustlings hint collections3` if you need
 // hints.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 fn fruit_basket() -> HashMap<String, u32> {
-    let mut basket = // TODO: declare your hash map here.
+    let mut basket = HashMap::new();
 
     // Two bananas are already given for you :)
     basket.insert(String::from("banana"), 2);
 
-    // TODO: Put more fruits in your basket here.
+    basket.insert(String::from("orange"), 3);
+    basket.insert(String::from("strawberry"), 5);
 
     basket
 }
@@ -39,8 +38,6 @@ mod tests {
     #[test]
     fn at_least_five_fruits() {
         let basket = fruit_basket();
-        assert!(basket
-            .values()
-            .sum::<u32>() >= 5);
+        assert!(basket.values().sum::<u32>() >= 5);
     }
 }

exercises/collections/hashmap2.rs

@@ -12,8 +12,6 @@
 // Execute the command `rustlings hint collections4` if you need
 // hints.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 #[derive(Hash, PartialEq, Eq)]
@@ -35,9 +33,7 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
     ];
 
     for fruit in fruit_kinds {
-        // TODO: Put new fruits if not already present. Note that you
-        // are not allowed to put any type of fruit that's already
-        // present!
+        basket.entry(fruit).or_insert(1);
     }
 }
 
@@ -75,9 +71,7 @@ mod tests {
     fn greater_than_eleven_fruits() {
         let mut basket = get_fruit_basket();
         fruit_basket(&mut basket);
-        let count = basket
-            .values()
-            .sum::<u32>();
+        let count = basket.values().sum::<u32>();
         assert!(count > 11);
     }
 }

exercises/collections/vec1.rs

@@ -4,11 +4,9 @@
 // Make me compile and pass the test!
 // Execute the command `rustlings hint collections1` if you need hints.
 
-// I AM NOT DONE
-
 fn array_and_vec() -> ([i32; 4], Vec<i32>) {
     let a = [10, 20, 30, 40]; // a plain array
-    let v = // TODO: declare your vector here with the macro for vectors
+    let v = vec![10, 20, 30, 40];
 
     (a, v)
 }

exercises/collections/vec2.rs

@@ -7,12 +7,9 @@
 // Execute the command `rustlings hint collections2` if you need
 // hints.
 
-// I AM NOT DONE
-
 fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
     for i in v.iter_mut() {
-        // TODO: Fill this up so that each element in the Vec `v` is
-        // multiplied by 2.
+        *i *= 2;
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
@@ -28,11 +25,6 @@ mod tests {
         let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
         let ans = vec_loop(v.clone());
 
-        assert_eq!(
-            ans,
-            v.iter()
-                .map(|x| x * 2)
-                .collect::<Vec<i32>>()
-        );
+        assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
     }
 }