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49 lines
1.2 KiB
Rust
49 lines
1.2 KiB
Rust
// A Vec of even numbers is given. Your task is to complete the loop so that
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// each number in the Vec is multiplied by 2.
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//
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// Make me pass the test!
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fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
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for element in v.iter_mut() {
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// TODO: Fill this up so that each element in the Vec `v` is
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// multiplied by 2.
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???
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}
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// At this point, `v` should be equal to [4, 8, 12, 16, 20].
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v
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}
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fn vec_map(v: &Vec<i32>) -> Vec<i32> {
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v.iter().map(|element| {
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// TODO: Do the same thing as above - but instead of mutating the
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// Vec, you can just return the new number!
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???
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}).collect()
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}
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fn main() {
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// You can optionally experiment here.
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_vec_loop() {
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let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
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let ans = vec_loop(v.clone());
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assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
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}
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#[test]
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fn test_vec_map() {
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let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
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let ans = vec_map(&v);
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assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
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}
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}
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