結果

問題 No.2012 Largest Triangle
ユーザー akakimidori
提出日時 2022-07-15 22:26:58
言語 Rust
(1.83.0 + proconio)
結果
AC  
実行時間 64 ms / 2,500 ms
コード長 3,857 bytes
コンパイル時間 16,334 ms
コンパイル使用メモリ 376,684 KB
実行使用メモリ 9,344 KB
最終ジャッジ日時 2024-06-27 21:20:20
合計ジャッジ時間 17,091 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 1
other AC * 41
権限があれば一括ダウンロードができます
コンパイルメッセージ
warning: unused import: `std::io::Write`
 --> src/main.rs:2:5
  |
2 | use std::io::Write;
  |     ^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: type alias `Map` is never used
 --> src/main.rs:4:6
  |
4 | type Map<K, V> = BTreeMap<K, V>;
  |      ^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: type alias `Set` is never used
 --> src/main.rs:5:6
  |
5 | type Set<T> = BTreeSet<T>;
  |      ^^^

warning: type alias `Deque` is never used
 --> src/main.rs:6:6
  |
6 | type Deque<T> = VecDeque<T>;
  |      ^^^^^

ソースコード

diff # 

use std::collections::*;
use std::io::Write;

type Map<K, V> = BTreeMap<K, V>;
type Set<T> = BTreeSet<T>;
type Deque<T> = VecDeque<T>;

fn run() {
    input! {
        n: usize,
        p: [(i64, i64); n],
    }
    let mut point = p;
    point.sort();
    if point.len() > 2 {
        let sign = |a: usize, b: usize, c: usize| -> i64 {
            let a = point[a];
            let b = point[b];
            let c = point[c];
            let ab = (b.0 - a.0, b.1 - a.1);
            let bc = (c.0 - b.0, c.1 - b.1);
            ab.0 * bc.1 - ab.1 * bc.0
        };
        let n = point.len();
        let mut hull = vec![0];
        let mut fix = 0;
        for i in (1..n).chain((0..(n - 1)).rev()) {
            while hull.len() > fix + 1 {
                let len = hull.len();
                if sign(hull[len - 2], hull[len - 1], i) >= 0 {
                    hull.pop();
                } else {
                    break;
                }
            }
            hull.push(i);
            if i == n - 1 {
                fix = hull.len() - 1;
            }
        }
        hull.pop();
        point = hull.into_iter().map(|k| point[k]).collect();
    }
    let mut p = point;
    let n = p.len();
    let mut ans = 0;
    for _ in 0..2 {
        argument_sort(&mut p);
        let mut pos = 0;
        for i in 0..n {
            let (x, y) = p[i];
            let mut f = |p: (i64, i64)| -> i64 {
                let s = x * p.1 - y * p.0;
                ans = ans.max(s.abs());
                s
            };
            if pos == i {
                pos = (pos + 1) % n;
            }
            while pos != i {
                let a = p[pos];
                let b = p[(pos + 1) % n];
                if f(a) <= f(b) {
                    pos = (pos + 1) % n;
                } else {
                    break;
                }
            }
        }
        p.iter_mut().for_each(|p| p.1 *= -1);
    }
    println!("{}", ans);
}

// https://judge.yosupo.jp/submission/27030 より
pub fn argument_sort(a: &mut [(i64, i64)]) {
    a.sort_by(|&(x1, y1), &(x2, y2)| {
        (y1 >= 0)
            .cmp(&(y2 >= 0))
            .then_with(|| (x2 as i64 * y1 as i64).cmp(&(x1 as i64 * y2 as i64)))
            .then_with(|| y1.cmp(&y2)) // (0, 0) < (x, y (> 0))
            .then_with(|| x2.cmp(&x1)) // (x1 (>= 0), 0) < (x2 (< 0), 0)
    });
}

fn main() {
    run();
}

// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[macro_export]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[macro_export]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[macro_export]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------
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