#631681 (Rust) No.1435 Mmm......

• 問題: No.1435 Mmm......
• ユーザー: akakimidori
• 提出日時: 2021-03-19 22:03:33
• 言語: Rust (1.83.0 + proconio)
• 結果: AC
• 実行時間: 38 ms / 2,000 ms
• コード長: 5,465 bytes
• コンパイル時間: 14,902 ms
• コンパイル使用メモリ: 396,800 KB
• 実行使用メモリ: 30,036 KB
• 最終ジャッジ日時: 2024-11-18 22:23:41
• 合計ジャッジ時間: 16,886 ms
• ジャッジサーバーID （参考情報）: judge5 / judge3

ファイルパターン	結果
sample	AC * 4
other	AC * 24

ソースコード

// ---------- begin Foldable Deque ----------
pub struct FoldableDeque<T, F> {
    front: Vec<(T, T)>,
    back: Vec<(T, T)>,
    op: F,
}

impl<T, F> FoldableDeque<T, F>
where
    T: Clone,
    F: Fn(&T, &T) -> T,
{
    pub fn new(op: F) -> Self {
        FoldableDeque {
            front: Vec::new(),
            back: Vec::new(),
            op: op,
        }
    }
    pub fn find(&self) -> Option<T> {
        match (self.front.last(), self.back.last()) {
            (Some(a), Some(b)) => Some((self.op)(&a.1, &b.1)),
            (Some(a), None) => Some(a.1.clone()),
            (None, Some(b)) => Some(b.1.clone()),
            (None, None) => None,
        }
    }
    pub fn clear(&mut self) {
        self.front.clear();
        self.back.clear();
    }
    pub fn len(&self) -> usize {
        self.front.len() + self.back.len()
    }
    pub fn push_back(&mut self, val: T) {
        let sum = self
            .back
            .last()
            .map_or_else(|| val.clone(), |p| (self.op)(&p.1, &val));
        self.back.push((val, sum));
    }
    pub fn push_front(&mut self, val: T) {
        let sum = self
            .front
            .last()
            .map_or_else(|| val.clone(), |p| (self.op)(&val, &p.1));
        self.front.push((val, sum));
    }
    pub fn pop_front(&mut self) -> Option<T> {
        if self.front.is_empty() {
            let a = self.back.clone();
            let m = (self.back.len() + 1) / 2;
            self.back.clear();
            let (f, b) = a.split_at(m);
            for v in f.iter().rev() {
                self.push_front(v.0.clone());
            }
            for v in b.iter() {
                self.push_back(v.0.clone());
            }
        }
        self.front.pop().map(|p| p.0)
    }
    pub fn pop_back(&mut self) -> Option<T> {
        if self.back.is_empty() {
            let a = self.front.clone();
            let m = (self.front.len() + 1) / 2;
            self.front.clear();
            let (f, b) = a.split_at(m);
            for v in b.iter() {
                self.push_front(v.0.clone());
            }
            for v in f.iter().rev() {
                self.push_back(v.0.clone());
            }
        }
        self.back.pop().map(|p| p.0)
    }
    pub fn front(&self) -> Option<&T> {
        self.front
            .last()
            .map_or_else(|| self.back.get(0).map(|p| &p.0), |p| Some(&p.0))
    }
    pub fn back(&self) -> Option<&T> {
        self.back
            .last()
            .map_or_else(|| self.front.get(0).map(|p| &p.0), |p| Some(&p.0))
    }
    pub fn get(&self, k: usize) -> Option<&T> {
        if let Some(po) = self.front.get(self.front.len() - 1 - k) {
            return Some(&po.0);
        }
        let k = k - self.front.len();
        self.back.get(k).map(|po| &po.0)
    }
}
// ---------- end Foldable Deque ----------
// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
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_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_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 ----------

fn run() {
    input! {
        n: usize,
        a: [u32; n],
    }
    let mut p = vec![(0, 0); n];
    for (i, a) in a.iter().enumerate() {
        p[i] = (*a, i as u32);
    }
    type T = (u32, u32);
    type E = (T, T, T);
    let merge = |a: &E, b: &E| -> E {
        let (x, y) = if a.0 < b.0 {
            (a.0, a.1.min(b.0))
        } else {
            (b.0, a.0.min(b.1))
        };
        (x, y, a.2.max(b.2))
    };
    let mut deq = FoldableDeque::new(merge);
    let mut ans = 0;
    let mut r = 0;
    let inf = std::u32::MAX / 2;
    for i in 0..(n - 1) {
        while r <= i + 1 {
            let a = p[r];
            r += 1;
            deq.push_back((a, (inf, inf), a));
        }
        while r < n {
            let (x, y, z) = deq.find().unwrap();
            if x.0 + y.0 < z.0 {
                break;
            }
            let a = p[r];
            r += 1;
            deq.push_back((a, (inf, inf), a));
        }
        let (x, y, z) = deq.find().unwrap();
        if x.0 + y.0 >= z.0 {
            ans += n - i - 1;
        } else {
            ans += r - i - 2;
        }
        deq.pop_front();
    }
    println!("{}", ans);
}

fn main() {
    run();
}