https://atcoder.jp/contests/math-and-algorithm/tasks/math_and_algorithm_br
これもしらみつぶしで十分です。
// Beautiful Rectangle #![allow(non_snake_case)] //////////////////// library //////////////////// fn read<T: std::str::FromStr>() -> T { let mut line = String::new(); std::io::stdin().read_line(&mut line).ok(); line.trim().parse().ok().unwrap() } //////////////////// process //////////////////// fn f(N: u64) -> u64 { let a: u64 = (1..).take_while(|n| n*n <= N). filter(|n| N%n == 0).last().unwrap(); 2 * (a + N/a) } fn main() { let N = read(); println!("{}", f(N)) }