use std::cmp::*; // 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, p: i64, h: [i64; n], } let mut acc_l = vec![0; n]; for i in 0..n - 1 { acc_l[i + 1] = acc_l[i] + max(0, h[i + 1] - h[i]); } let mut acc_r = vec![0; n]; for i in (0..n - 1).rev() { acc_r[i] = acc_r[i + 1] + max(0, h[i] - h[i + 1]); } let mut dp = vec![0; n + 1]; let mut mim = 0; let mut mip = acc_r[0]; for j in 1..n + 1 { dp[j] = min(mim + acc_l[j - 1], mip - acc_r[j - 1]) + p; if j < n { mim = min(mim, dp[j] - acc_l[j]); mip = min(mip, dp[j] + acc_r[j]); } } println!("{}", dp[n] - p); }