競プロ典型 020

https://atcoder.jp/contests/typical90/tasks/typical90_t

か調べればよいですが、cのべき乗を次々と計算していけばよいです。

// Log Inequality
#![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()
}

fn YesNo(b: bool) -> String {
    return if b { "Yes" } else { "No" }.to_string()
}


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

fn read_input() -> (u64, u64, u64) {
    let v = read_vec();
    let (a, b, c) = (v[0], v[1], v[2]);
    (a, b, c)
}

fn F(a: u64, b: u64, c: u64) -> bool {
    // log2a < blog2c
    // a < c^b
    let mut p: u64 = 1;
    for _ in 0..b {
        if a / c < p {
            return true
        }
        p *= c
    }
    false
}

fn main() {
    let (a, b, c) = read_input();
    println!("{}", YesNo(F(a, b, c)))
}