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rustlings/exercises/vecs/vecs2.rs

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// vecs2.rs
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// A Vec of even numbers is given. Your task is to complete the loop
// so that each number in the Vec is multiplied by 2.
//
// Make me pass the test!
//
// Execute `rustlings hint vecs2` or use the `hint` watch subcommand for a hint.
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// I AM NOT DONE
fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
for element in v.iter_mut() {
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// TODO: Fill this up so that each element in the Vec `v` is
// multiplied by 2.
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???
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}
// At this point, `v` should be equal to [4, 8, 12, 16, 20].
v
}
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fn vec_map(v: &Vec<i32>) -> Vec<i32> {
v.iter().map(|element| {
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// TODO: Do the same thing as above - but instead of mutating the
// Vec, you can just return the new number!
???
}).collect()
}
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#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_vec_loop() {
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>>());
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}
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#[test]
fn test_vec_map() {
let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
let ans = vec_map(&v);
assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
}
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}