use std::cmp::*; use std::collections::*; // https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 macro_rules! input { ($($r:tt)*) => { let stdin = std::io::stdin(); let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock())); let mut next = move || -> String{ bytes.by_ref().map(|r|r.unwrap() as char) .skip_while(|c|c.is_whitespace()) .take_while(|c|!c.is_whitespace()) .collect() }; input_inner!{next, $($r)*} }; } macro_rules! input_inner { ($next:expr) => {}; ($next:expr,) => {}; ($next:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($next, $t); input_inner!{$next $($r)*} }; } macro_rules! read_value { ($next:expr, [ $t:tt ; $len:expr ]) => { (0..$len).map(|_| read_value!($next, $t)).collect::>() }; ($next:expr, $t:ty) => ($next().parse::<$t>().expect("Parse error")); } fn main() { input! { n: usize, k: usize, a: [i64; n], } let mut ma = 0; let mut tot = 0; let mut que = BinaryHeap::new(); for i in (0..n).rev() { if i % 2 == 1 { ma = max(ma, tot + a[i]); } que.push(Reverse(a[i])); tot += a[i]; if que.len() > k - 1 { let Reverse(v) = que.pop().unwrap(); tot -= v; } } println!("{}", ma); }