アルゴリズムと数学 072

https://atcoder.jp/contests/math-and-algorithm/tasks/jsc2021_c

gcdはなので、dを1から順に代入していけばよいです。

// Max GCD 2
#![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()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
            .map(|e| e.parse().ok().unwrap()).collect()
}


//////////////////// process ////////////////////

fn read_input() -> (i32, i32) {
    let v = read_vec();
    let A = v[0];
    let B = v[1];
    (A, B)
}

fn f(A: i32, B: i32) -> i32 {
    for d in 1..B+1 {
        let D = B / d;
        let a = D * (d - 1);
        if a >= A {
            return D
        }
    }
    1
}

fn main() {
    let (A, B) = read_input();
    println!("{}", f(A, B))
}