#[doc = " https://github.com/hatoo/competitive-rust-snippets"] #[allow(unused_imports)] use std::cmp::{max, min, Ordering}; #[allow(unused_imports)] use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque}; #[allow(unused_imports)] use std::io::{stdin, stdout, BufWriter, Write}; #[allow(unused_imports)] use std::iter::FromIterator; #[macro_export] macro_rules ! chmax { ( $ x : expr , $ ( $ v : expr ) ,+ ) => { $ ( $ x = std :: cmp :: max ( $ x ,$ v ) ; ) + } ; } #[macro_export] macro_rules ! chmin { ( $ x : expr , $ ( $ v : expr ) ,+ ) => { $ ( $ x = std :: cmp :: min ( $ x ,$ v ) ; ) + } ; } #[macro_export] macro_rules ! max { ( $ x : expr ) => ( $ x ) ; ( $ x : expr , $ ( $ xs : expr ) ,+ ) => { std :: cmp :: max ( $ x , max ! ( $ ( $ xs ) ,+ ) ) } ; } #[macro_export] macro_rules ! min { ( $ x : expr ) => ( $ x ) ; ( $ x : expr , $ ( $ xs : expr ) ,+ ) => { std :: cmp :: min ( $ x , min ! ( $ ( $ xs ) ,+ ) ) } ; } #[macro_export] macro_rules ! dvec { ( $ t : expr ; $ len : expr ) => { vec ! [ $ t ; $ len ] } ; ( $ t : expr ; $ len : expr , $ ( $ rest : expr ) ,* ) => { vec ! [ dvec ! ( $ t ; $ ( $ rest ) ,* ) ; $ len ] } ; } #[allow(unused_macros)] macro_rules ! debug { ( $ ( $ a : expr ) ,* ) => { eprintln ! ( concat ! ( $ ( stringify ! ( $ a ) , " = {:?}, " ) ,* ) , $ ( $ a ) ,* ) ; } } #[macro_export] macro_rules ! input { ( source = $ s : expr , $ ( $ r : tt ) * ) => { let mut parser = Parser :: from_str ( $ s ) ; input_inner ! { parser , $ ( $ r ) * } } ; ( parser = $ parser : ident , $ ( $ r : tt ) * ) => { input_inner ! { $ parser , $ ( $ r ) * } } ; ( new_stdin_parser = $ parser : ident , $ ( $ r : tt ) * ) => { let stdin = std :: io :: stdin ( ) ; let reader = std :: io :: BufReader :: new ( stdin . lock ( ) ) ; let mut $ parser = Parser :: new ( reader ) ; input_inner ! { $ parser , $ ( $ r ) * } } ; ( $ ( $ r : tt ) * ) => { input ! { new_stdin_parser = parser , $ ( $ r ) * } } ; } #[macro_export] macro_rules ! input_inner { ( $ parser : ident ) => { } ; ( $ parser : ident , ) => { } ; ( $ parser : ident , $ var : ident : $ t : tt $ ( $ r : tt ) * ) => { let $ var = read_value ! ( $ parser , $ t ) ; input_inner ! { $ parser $ ( $ r ) * } } ; } #[macro_export] macro_rules ! read_value { ( $ parser : ident , ( $ ( $ t : tt ) ,* ) ) => { ( $ ( read_value ! ( $ parser , $ t ) ) ,* ) } ; ( $ parser : ident , [ $ t : tt ; $ len : expr ] ) => { ( 0 ..$ len ) . map ( | _ | read_value ! ( $ parser , $ t ) ) . collect ::< Vec < _ >> ( ) } ; ( $ parser : ident , chars ) => { read_value ! ( $ parser , String ) . chars ( ) . collect ::< Vec < char >> ( ) } ; ( $ parser : ident , usize1 ) => { read_value ! ( $ parser , usize ) - 1 } ; ( $ parser : ident , $ t : ty ) => { $ parser . next ::<$ t > ( ) . expect ( "Parse error" ) } ; } use std::io; use std::io::BufRead; use std::str; pub struct Parser { reader: R, buf: Vec, pos: usize, } impl Parser { pub fn from_str(s: &str) -> Parser { Parser { reader: io::empty(), buf: s.as_bytes().to_vec(), pos: 0, } } } impl Parser { pub fn new(reader: R) -> Parser { Parser { reader: reader, buf: vec![], pos: 0, } } pub fn update_buf(&mut self) { self.buf.clear(); self.pos = 0; loop { let (len, complete) = { let buf2 = self.reader.fill_buf().unwrap(); self.buf.extend_from_slice(buf2); let len = buf2.len(); if len == 0 { break; } (len, buf2[len - 1] <= 0x20) }; self.reader.consume(len); if complete { break; } } } pub fn next(&mut self) -> Result { loop { let mut begin = self.pos; while begin < self.buf.len() && (self.buf[begin] <= 0x20) { begin += 1; } let mut end = begin; while end < self.buf.len() && (self.buf[end] > 0x20) { end += 1; } if begin != self.buf.len() { self.pos = end; return str::from_utf8(&self.buf[begin..end]).unwrap().parse::(); } else { self.update_buf(); } } } } #[allow(unused_macros)] macro_rules ! debug { ( $ ( $ a : expr ) ,* ) => { eprintln ! ( concat ! ( $ ( stringify ! ( $ a ) , " = {:?}, " ) ,* ) , $ ( $ a ) ,* ) ; } } #[doc = " https://github.com/hatoo/competitive-rust-snippets"] const BIG_STACK_SIZE: bool = true; #[allow(dead_code)] fn main() { use std::thread; if BIG_STACK_SIZE { thread::Builder::new() .stack_size(32 * 1024 * 1024) .name("solve".into()) .spawn(solve) .unwrap() .join() .unwrap(); } else { solve(); } } #[doc = "lower,upper are inclusive range"] pub struct BinarySearch { pub p: F, pub lower: i64, pub upper: i64, } impl bool> BinarySearch { #[doc = "O(log(upper-lower))"] pub fn lower_bound(&self) -> i64 { let lower = self.lower; let upper = self.upper; assert!(lower <= upper); let mut lb = lower - 1; let mut ub = upper + 1; while ub - lb > 1 { let mid = (lb + ub) / 2; if (self.p)(mid) { ub = mid; } else { lb = mid; } } let latter = ub; latter } } fn solve() { input!{ n:usize, a:[i64;n] } let mut a = a; a.sort(); let mut cum = CumSum1::new(n); for i in 0..n { cum.set(i, a[i]); } cum.build(); let mut maxv = 0; // 1つとるケース for i in 0..n { let m = a[i]; let bs = BinarySearch { lower: 0, upper: min(i as i64, (n-i-1) as i64), p: |w: i64| { if w == 0 { return false } let w = w as usize; let l = i-w; let r = n-w; a[r]+a[l]<2*m } }; let r = bs.lower_bound() as usize; let l = r - 1; let v = cum.query(i-l, i) + cum.query(n-l, n) - 2 * l as i64 * m; chmax!(maxv, v); } // 2つとるケース for i in 0..n-1 { let m0 = a[i]; let m1 = a[i+1]; let bs = BinarySearch { lower: 0, upper: min(i as i64, (n-i-2) as i64), p: |w: i64| { if w == 0 { return false } let w = w as usize; let l = i-w; let r = n-w; a[r]+a[l] < m0+m1 }, }; let r = bs.lower_bound() as usize; let l = r - 1; let v = cum.query(i-l, i) + cum.query(n-l, n) - l as i64 * (m0+m1); chmax!(maxv, v); } println!("{}", maxv); } // とりあえずN^2解法 fn solve_n2() { let out = stdout(); let mut out = BufWriter::new(out.lock()); input!{ n:usize, a:[i64;n] } let mut a = a; a.sort(); let mut cum = CumSum1::new(n); for i in 0..n { cum.set(i, a[i]); } cum.build(); // kが決まってる時の最適値は計算出来る // O(N) let calc = |k: usize| { if k%2 == 1 { // 奇数ケース let mut maxv = 0; for i in 0..n { let m = a[i]; let L = (k-1)/2; let R = (k-1)/2; if i+R >= n { continue; } if i= n { continue; } if i, dp: Vec, } impl CumSum1 { fn new(n: usize) -> CumSum1 { CumSum1 { base: vec![0; n], dp: vec![], } } fn add(&mut self, i: usize, x: i64) { self.base[i] += x; } fn set(&mut self, i: usize, x: i64) { self.base[i] = x; } fn build(&mut self) { let n = self.base.len(); let mut dp = vec![0; n + 1]; let mut acc = 0; for i in 0..n { acc += self.base[i]; dp[i + 1] = acc; } self.dp = dp; } #[doc = "[i,j)"] fn query(&self, i: usize, j: usize) -> i64 { self.dp[j] - self.dp[i] } }