Module b
Expand description
ยงABC 392 B - Who is Missing?
refs: https://atcoder.jp/contests/abc392/tasks/abc392_b
use std::collections::HashSet;
use proconio::input;
fn main() {
input! {
n: usize, m: usize,
a: [usize; m],
}
let mut set = HashSet::new();
for ai in a {
set.insert(ai);
}
let mut ans = Vec::new();
for i in 1..=n {
if !set.contains(&i) {
ans.push(i);
}
}
println!("{}", ans.len());
println!(
"{}",
ans.iter()
.map(|i| i.to_string())
.collect::<Vec<_>>()
.join(" ")
);
}