mirror of
https://github.com/rust-lang/rustlings.git
synced 2026-01-11 13:19:18 +00:00
37 lines
948 B
Rust
37 lines
948 B
Rust
// vec2.rs
|
||
// 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 the command `rustlings hint vec2` if you need
|
||
// hints.
|
||
|
||
|
||
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.
|
||
// not so obvious answer, this is because multiplication is a right action in Rust <20><>
|
||
*i = *i*2;
|
||
// slick answer below
|
||
//*i *= 2; // pythonish: i = 2*i
|
||
}
|
||
|
||
// At this point, `v` should be equal to [4, 8, 12, 16, 20].
|
||
v
|
||
}
|
||
|
||
#[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>>());
|
||
}
|
||
}
|