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Add a method that solves the problem: using recursion combined with match to implement factorial.

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This commit is contained in:
1vk3y 2024-10-19 18:35:47 +08:00
parent 930a0ea73b
commit 04407ae27e
1 changed files with 13 additions and 1 deletions
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14
solutions/18_iterators/iterators4.rs
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@ -1,4 +1,4 @@
// 3 possible solutions are presented. // 4 possible solutions are presented.
// With `for` loop and a mutable variable. // With `for` loop and a mutable variable.
fn factorial_for(num: u64) -> u64 { fn factorial_for(num: u64) -> u64 {
@ -35,6 +35,14 @@ fn factorial_product(num: u64) -> u64 {
(2..=num).product() (2..=num).product()
} }
// Using recursion in conjunction with the `match` to implement factorial
fn factorial_recursion(num: u64) -> u64 {
match num {
0..=1 => 1,
_ => num * factorial_recursion(num - 1),
}
}
fn main() { fn main() {
// You can optionally experiment here. // You can optionally experiment here.
} }
@ -48,6 +56,7 @@ mod tests {
assert_eq!(factorial_for(0), 1); assert_eq!(factorial_for(0), 1);
assert_eq!(factorial_fold(0), 1); assert_eq!(factorial_fold(0), 1);
assert_eq!(factorial_product(0), 1); assert_eq!(factorial_product(0), 1);
assert_eq!(factorial_recursion(0), 1);
} }
#[test] #[test]
@ -55,12 +64,14 @@ mod tests {
assert_eq!(factorial_for(1), 1); assert_eq!(factorial_for(1), 1);
assert_eq!(factorial_fold(1), 1); assert_eq!(factorial_fold(1), 1);
assert_eq!(factorial_product(1), 1); assert_eq!(factorial_product(1), 1);
assert_eq!(factorial_recursion(1), 1);
} }
#[test] #[test]
fn factorial_of_2() { fn factorial_of_2() {
assert_eq!(factorial_for(2), 2); assert_eq!(factorial_for(2), 2);
assert_eq!(factorial_fold(2), 2); assert_eq!(factorial_fold(2), 2);
assert_eq!(factorial_product(2), 2); assert_eq!(factorial_product(2), 2);
assert_eq!(factorial_recursion(2), 2);
} }
#[test] #[test]
@ -68,5 +79,6 @@ mod tests {
assert_eq!(factorial_for(4), 24); assert_eq!(factorial_for(4), 24);
assert_eq!(factorial_fold(4), 24); assert_eq!(factorial_fold(4), 24);
assert_eq!(factorial_product(4), 24); assert_eq!(factorial_product(4), 24);
assert_eq!(factorial_recursion(4), 24);
} }
} }