AtCoder Beginner Contest 240 B

https://atcoder.jp/contests/abc240/tasks/abc240_b

Traitの指定にwhereを使うとちょっときれいに書けます。

// Count Distinct Integers
#![allow(non_snake_case)]

use std::collections::HashSet;

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_set<T>() -> HashSet<T>
    where T: std::str::FromStr + std::cmp::Eq + std::hash::Hash {
    read::<String>().split_whitespace()
            .map(|e| e.parse().ok().unwrap()).collect()
}

fn main() {
    let _N: usize = read();
    let A: HashSet<i32> = read_set();
    println!("{}", A.len())
}