HashSet contains solution

playground.rs

use std::collections::HashSet;

fn contains<T, Q>(arr: &HashSet<T>, value: &Q) -> bool
where
    T: std::cmp::PartialEq<Q>,
{
    arr.iter().any(|v| v == value)
}

fn main() {
    let hs_str: HashSet<&str> = ["a", "b", "c"].iter().copied().collect();
    let hs_string: HashSet<String> = vec!["a".to_string(), "b".to_string(), "c".to_string()]
        .into_iter()
        .collect();

    let value_str = "b";
    let value_string = String::from(value_str);

    let result_str = contains(&hs_str, &value_string);
    let result_string = contains(&hs_string, &value_str);
    let result_literal = contains(&hs_string, &"a"); // need to a &

    println!(
        "result: {} {} {}",
        result_str, result_string, result_literal
    );
}