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programming-rust-examples/gcd/src/main.rs

50 lines
956 B
Rust

#![warn(rust_2018_idioms)]
#![allow(elided_lifetimes_in_paths)]
fn gcd(mut n: u64, mut m: u64) -> u64 {
assert!(n != 0 && m != 0);
while m != 0 {
if m < n {
let t = m;
m = n;
n = t;
}
m = m % n;
}
n
}
#[test]
fn test_gcd() {
assert_eq!(gcd(14, 15), 1);
assert_eq!(gcd(2 * 3 * 5 * 11 * 17,
3 * 7 * 11 * 13 * 19),
3 * 11);
}
use std::str::FromStr;
use std::env;
fn main() {
let mut numbers = Vec::new();
for arg in env::args().skip(1) {
numbers.push(u64::from_str(&arg)
.expect("error parsing argument"));
}
if numbers.len() == 0 {
eprintln!("Usage: gcd NUMBER ...");
std::process::exit(1);
}
let mut d = numbers[0];
for m in &numbers[1..] {
d = gcd(d, *m);
}
println!("The greatest common divisor of {:?} is {}",
numbers, d);
}