fn main() {
for i in 1..=6 {
println!("{}! = {}", i, factorial(i));
}
}
fn factorial(n: u32) -> u32 {
let mut a = 1;
for i in 2..=n {
a *= i;
}
a
}
#[test]
fn test_factorial() {
println!("factorial({}) = {}", 6, factorial(6)); assert_eq!(factorial(6), 720);
}