アルゴリズムと数学 088

https://atcoder.jp/contests/math-and-algorithm/tasks/arc107_a

$\displaystyle \sum_{a=1}^A{\sum_{b=1}^B{\sum_{c=1}^C{abc}}} = \sum_{a=1}^A{a}\sum_{b=1}^B{b}\sum_{c=1}^C{c}$
ですね。

// Simple Math
#![allow(non_snake_case)]


//////////////////// constants ////////////////////

const D: u64 = 998244353;


//////////////////// 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() -> (u64, u64, u64) {
    let v = read_vec();
    let A = v[0];
    let B = v[1];
    let C = v[2];
    (A, B, C)
}

fn T(N: u64) -> u64 {
    if N % 2 == 0 {
        (N / 2) * (N + 1) % D
    }
    else {
        N * ((N + 1) / 2) % D
    }
}

fn f(A: u64, B: u64, C: u64) -> u64 {
    T(A) * T(B) % D * T(C) % D
}

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