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56 lines
1.4 KiB
Rust
56 lines
1.4 KiB
Rust
fn vec_loop(input: &[i32]) -> Vec<i32> {
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let mut output = Vec::new();
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for element in input {
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output.push(2 * element);
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}
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output
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}
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fn vec_map_example(input: &[i32]) -> Vec<i32> {
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// An example of collecting a vector after mapping.
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// We map each element of the `input` slice to its value plus 1.
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// If the input is `[1, 2, 3]`, the output is `[2, 3, 4]`.
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input.iter().map(|element| element + 1).collect()
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}
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fn vec_map(input: &[i32]) -> Vec<i32> {
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// We will dive deeper into iterators, but for now, this is all what you
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// had to do!
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// Advanced note: This method is more efficient because it automatically
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// preallocates enough capacity. This can be done manually in `vec_loop`
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// using `Vec::with_capacity(input.len())` instead of `Vec::new()`.
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input.iter().map(|element| 2 * element).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 input = [2, 4, 6, 8, 10];
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let ans = vec_loop(&input);
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assert_eq!(ans, [4, 8, 12, 16, 20]);
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}
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#[test]
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fn test_vec_map_example() {
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let input = [1, 2, 3];
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let ans = vec_map_example(&input);
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assert_eq!(ans, [2, 3, 4]);
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}
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#[test]
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fn test_vec_map() {
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let input = [2, 4, 6, 8, 10];
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let ans = vec_map(&input);
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assert_eq!(ans, [4, 8, 12, 16, 20]);
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}
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}
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