Rust Sample - HashMap

use std::io;
use std::collections::HashMap;

fn main() -> io::Result<()> {
    let hash_map: HashMap<char, usize> = [
        ('A', 3), ('B', 3), ('C', 3),
        ('D', 4), ('E', 4), ('F', 4),
        ('G', 5), ('H', 5), ('I', 5),
        ('J', 6), ('K', 6), ('L', 6),
        ('M', 7), ('N', 7), ('O', 7),
        ('P', 8), ('Q', 8), ('R', 8), ('S', 8),
        ('T', 9), ('U', 9), ('V', 9),
        ('W', 10), ('X', 10), ('Y', 10), ('Z', 10),
    ].iter().copied().collect();

    let mut input = String::new();
    io::stdin().read_line(&mut input)?;

    let ans: usize = input.trim()
        .chars()
        .filter_map(|c| hash_map.get(&c))
        .sum();
    println!("{}", ans);

    Ok(())
}