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rustlings-exercises-completed/exercises/iterators/iterators4.rs

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// iterators4.rs
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// Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a hint.
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pub fn factorial(num: u64) -> u64 {
// Complete this function to return the factorial of num
// Do not use:
// - return
// Try not to use:
// - imperative style loops (for, while)
// - additional variables
// For an extra challenge, don't use:
// - recursion
// Execute `rustlings hint iterators4` for hints.
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(1..=num).product()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn factorial_of_0() {
assert_eq!(1, factorial(0));
}
#[test]
fn factorial_of_1() {
assert_eq!(1, factorial(1));
}
#[test]
fn factorial_of_2() {
assert_eq!(2, factorial(2));
}
#[test]
fn factorial_of_4() {
assert_eq!(24, factorial(4));
}
}