Discussion on: Daily Coding Problem #1

use std::collections::HashSet;

fn two_add_upto(list: &[i32], k: i32) -> bool {
    let mut set = HashSet::with_capacity(list.len());

    for i in list.iter() {
        let diff = k - i;
        if set.contains(&diff) {
            return true;
        }
        set.insert(i);
    }
    false
}