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Rust で解く 1 から max までのすべての自然数の最小公倍数 ref: http://qiita.com/mhgp/items/711a7bb8e00bff607660
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///a と b の最大公約数を求める | |
fn gcd(a: usize, b: usize) -> usize { | |
if a % b == 0 { | |
b | |
} else { | |
gcd(b, a % b) | |
} | |
} | |
///ループ処理 | |
fn solve(max: usize) -> usize { | |
(2..max + 1).fold(1, |lcm, n| { | |
(n * lcm) / gcd(n, lcm) | |
}) | |
} | |
///1 から max までのすべての自然数の最小公倍数を求める | |
pub fn get_lcm(max: usize) -> usize { | |
assert!(max > 2); | |
solve(max) | |
} |
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mod stack { | |
///a と b の最大公約数を求める | |
fn gcd(a: usize, b: usize) -> usize { | |
if a % b == 0 { | |
b | |
} else { | |
gcd(b, a % b) | |
} | |
} | |
///ループ処理 | |
fn solve(n: usize, lcm: usize, max: usize) -> usize { | |
if n <= max { | |
solve(n + 1, (n * lcm) / gcd(n, lcm), max) | |
} else { | |
lcm | |
} | |
} | |
///1 から max までのすべての自然数の最小公倍数を求める | |
pub fn get_lcm(max: usize) -> usize { | |
assert!(max > 2); | |
solve(2, 1, max) | |
} | |
} | |
mod fold { | |
///a と b の最大公約数を求める | |
fn gcd(a: usize, b: usize) -> usize { | |
if a % b == 0 { | |
b | |
} else { | |
gcd(b, a % b) | |
} | |
} | |
///ループ処理 | |
fn solve(max: usize) -> usize { | |
(2..max + 1).fold(1, |lcm, n| { | |
(n * lcm) / gcd(n, lcm) | |
}) | |
} | |
///1 から max までのすべての自然数の最小公倍数を求める | |
pub fn get_lcm(max: usize) -> usize { | |
assert!(max > 2); | |
solve(max) | |
} | |
} | |
mod procedural { | |
///a と b の最大公約数を求める | |
fn gcd(a: usize, b: usize) -> usize { | |
let (mut a, mut b) = if a < b { | |
(b, a) | |
} else { | |
(a, b) | |
}; | |
while b > 0 { | |
let r = a % b; | |
a = b; | |
b = r; | |
} | |
a | |
} | |
///ループ処理 | |
fn solve(max: usize) -> usize { | |
let mut lcm = 1; | |
for n in 2..max + 1 { | |
lcm = (n * lcm) / gcd(n, lcm); | |
} | |
lcm | |
} | |
///1 から max までのすべての自然数の最小公倍数を求める | |
pub fn get_lcm(max: usize) -> usize { | |
assert!(max > 2); | |
solve(max) | |
} | |
} | |
mod mix { | |
///a と b の最大公約数を求める | |
fn gcd(a: usize, b: usize) -> usize { | |
let (mut a, mut b) = if a < b { | |
(b, a) | |
} else { | |
(a, b) | |
}; | |
while b > 0 { | |
let r = a % b; | |
a = b; | |
b = r; | |
} | |
a | |
} | |
///ループ処理 | |
fn solve(max: usize) -> usize { | |
(2..max + 1).fold(1, |lcm, n| { | |
(n * lcm) / gcd(n, lcm) | |
}) | |
} | |
///1 から max までのすべての自然数の最小公倍数を求める | |
pub fn get_lcm(max: usize) -> usize { | |
assert!(max > 2); | |
solve(max) | |
} | |
} | |
fn main() { | |
assert_eq!(stack::get_lcm(10) , 2520); | |
assert_eq!(stack::get_lcm(20) , 232792560); | |
assert_eq!(stack::get_lcm(11) , 27720); | |
assert_eq!(fold::get_lcm(10) , 2520); | |
assert_eq!(fold::get_lcm(20) , 232792560); | |
assert_eq!(fold::get_lcm(11) , 27720); | |
assert_eq!(procedural::get_lcm(10) , 2520); | |
assert_eq!(procedural::get_lcm(20) , 232792560); | |
assert_eq!(procedural::get_lcm(11) , 27720); | |
assert_eq!(mix::get_lcm(10) , 2520); | |
assert_eq!(mix::get_lcm(20) , 232792560); | |
assert_eq!(mix::get_lcm(11) , 27720); | |
println!("All Ok!"); | |
} |
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///a と b の最大公約数を求める | |
fn gcd(a: usize, b: usize) -> usize { | |
let (mut a, mut b) = if a < b { | |
(b, a) | |
} else { | |
(a, b) | |
}; | |
while b > 0 { | |
let r = a % b; | |
a = b; | |
b = r; | |
} | |
a | |
} | |
///ループ処理 | |
fn solve(max: usize) -> usize { | |
(2..max + 1).fold(1, |lcm, n| { | |
(n * lcm) / gcd(n, lcm) | |
}) | |
} | |
///1 から max までのすべての自然数の最小公倍数を求める | |
pub fn get_lcm(max: usize) -> usize { | |
assert!(max > 2); | |
solve(max) | |
} |
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///a と b の最大公約数を求める | |
fn gcd(a: usize, b: usize) -> usize { | |
let (mut a, mut b) = if a < b { | |
(b, a) | |
} else { | |
(a, b) | |
}; | |
while b > 0 { | |
let r = a % b; | |
a = b; | |
b = r; | |
} | |
a | |
} | |
///ループ処理 | |
fn solve(max: usize) -> usize { | |
let mut lcm = 1; | |
for n in 2..max + 1 { | |
lcm = (n * lcm) / gcd(n, lcm); | |
} | |
lcm | |
} | |
///1 から max までのすべての自然数の最小公倍数を求める | |
pub fn get_lcm(max: usize) -> usize { | |
assert!(max > 2); | |
solve(max) | |
} |
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///a と b の最大公約数を求める | |
fn gcd(a: usize, b: usize) -> usize { | |
if a % b == 0 { | |
b | |
} else { | |
gcd(b, a % b) | |
} | |
} | |
///ループ処理 | |
fn solve(n: usize, lcm: usize, max: usize) -> usize { | |
if n <= max { | |
solve(n + 1, (n * lcm) / gcd(n, lcm), max) | |
} else { | |
lcm | |
} | |
} | |
///1 から max までのすべての自然数の最小公倍数を求める | |
pub fn get_lcm(max: usize) -> usize { | |
assert!(max > 2); | |
solve(2, 1, max) | |
} |
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