Initial commit

exercises/05_vecs/README.md

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+# Vectors
+
+Vectors are one of the most-used Rust data structures. In other programming
+languages, they'd simply be called Arrays, but since Rust operates on a
+bit of a lower level, an array in Rust is stored on the stack (meaning it
+can't grow or shrink, and the size needs to be known at compile time),
+and a Vector is stored in the heap (where these restrictions do not apply).
+
+Vectors are a bit of a later chapter in the book, but we think that they're
+useful enough to talk about them a bit earlier. We shall be talking about
+the other useful data structure, hash maps, later.
+
+## Further information
+
+- [Storing Lists of Values with Vectors](https://doc.rust-lang.org/book/ch08-01-vectors.html)
+- [`iter_mut`](https://doc.rust-lang.org/std/primitive.slice.html#method.iter_mut)
+- [`map`](https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.map)

exercises/05_vecs/vecs1.rs

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+fn array_and_vec() -> ([i32; 4], Vec<i32>) {
+    let a = [10, 20, 30, 40]; // Array
+
+    // TODO: Create a vector called `v` which contains the exact same elements as in the array `a`.
+    // Use the vector macro.
+    // let v = ???;
+    let v = vec![10, 20, 30, 40];
+
+    (a, v)
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_array_and_vec_similarity() {
+        let (a, v) = array_and_vec();
+        assert_eq!(a, *v);
+    }
+}

exercises/05_vecs/vecs2.rs

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+fn vec_loop(input: &[i32]) -> Vec<i32> {
+    let mut output = Vec::new();
+
+    for element in input {
+        // TODO: Multiply each element in the `input` slice by 2 and push it to
+        // the `output` vector.
+        output.push(element * 2);
+    }
+
+    output
+}
+
+fn vec_map_example(input: &[i32]) -> Vec<i32> {
+    // An example of collecting a vector after mapping.
+    // We map each element of the `input` slice to its value plus 1.
+    // If the input is `[1, 2, 3]`, the output is `[2, 3, 4]`.
+    input.iter().map(|element| element + 1).collect()
+}
+
+fn vec_map(input: &[i32]) -> Vec<i32> {
+    // TODO: Here, we also want to multiply each element in the `input` slice
+    // by 2, but with iterator mapping instead of manually pushing into an empty
+    // vector.
+    // See the example in the function `vec_map_example` above.
+    input.iter().map(|element| element * 2).collect()
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_vec_loop() {
+        let input = [2, 4, 6, 8, 10];
+        let ans = vec_loop(&input);
+        assert_eq!(ans, [4, 8, 12, 16, 20]);
+    }
+
+    #[test]
+    fn test_vec_map_example() {
+        let input = [1, 2, 3];
+        let ans = vec_map_example(&input);
+        assert_eq!(ans, [2, 3, 4]);
+    }
+
+    #[test]
+    fn test_vec_map() {
+        let input = [2, 4, 6, 8, 10];
+        let ans = vec_map(&input);
+        assert_eq!(ans, [4, 8, 12, 16, 20]);
+    }
+}