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rustlings/exercises/05_vecs/vecs2.rs

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Rust

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
}
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| {
// ???
})
.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]);
}
}