#1159400 (Rust) No.3504 Insert Maze

• 問題: No.3504 Insert Maze
• ユーザー: akakimidori
• 提出日時: 2026-04-18 10:52:22
• 言語: Rust (1.94.0 + proconio + num + itertools)
• 結果: AC
• 実行時間: 414 ms / 2,000 ms
• コード長: 4,174 bytes
• コンパイル時間: 15,079 ms
• コンパイル使用メモリ: 200,004 KB
• 実行使用メモリ: 104,008 KB
• 最終ジャッジ日時: 2026-04-18 10:52:51
• 合計ジャッジ時間: 21,287 ms
• ジャッジサーバーID （参考情報）: judge3_0 / judge1_0

ファイルパターン	結果
sample	AC * 3
other	AC * 85

ソースコード

fn main() {
    input! {
        h: usize,
        w: usize,
        s: [bytes; h],
    }
    let g = Grid::new(h, w);
    let bfs = |src: (usize, usize)| -> Vec<Vec<usize>> {
        let mut dp = vec![vec![h * w; w]; h];
        dp[src.0][src.1] = 0;
        let mut deq = std::collections::VecDeque::new();
        deq.push_back(src);
        while let Some((x, y)) = deq.pop_front() {
            let d = dp[x][y] + 1;
            for (x, y) in g.four(x, y) {
                if s[x][y] != b'#' && dp[x][y] > d {
                    dp[x][y] = d;
                    deq.push_back((x, y));
                }
            }
        }
        dp
    };
    let mut a = bfs((0, 0));
    let mut b = bfs((h - 1, w - 1));
    let mut ans = h + w;
    ans = ans.min(a[h - 1][w - 1]);
    for _ in 0..2 {
        let h = a.len();
        let w = a[0].len();
        for i in 1..h {
            let a = &a[i - 1];
            let b = &b[i];
            let mut val = ans + 10;
            for j in 0..w {
                val = val.min(a[j] - j);
                ans = ans.min(val + b[j] + j + 2);
            }
        }
        a = transpose(a);
        b = transpose(b);
    }
    println!("{}", ans);
}

#[derive(Clone)]
pub struct Grid {
    h: usize,
    w: usize,
}

impl Grid {
    pub fn new(h: usize, w: usize) -> Self {
        Self { h, w }
    }
    pub fn four(&self, x: usize, y: usize) -> impl Iterator<Item = (usize, usize)> + '_ {
        const DX: [usize; 4] = [0, 1, 0, !0];
        const DY: [usize; 4] = [1, 0, !0, 0];
        self.generator(x, y, DX.iter().zip(DY.iter()).map(|p| (*p.0, *p.1)))
    }
    pub fn eight(&self, x: usize, y: usize) -> impl Iterator<Item = (usize, usize)> + '_ {
        const DX: [usize; 8] = [0, 1, 1, 1, 0, !0, !0, !0];
        const DY: [usize; 8] = [1, 1, 0, !0, !0, !0, 0, 1];
        self.generator(x, y, DX.iter().zip(DY.iter()).map(|p| (*p.0, *p.1)))
    }
    pub fn generator<'a, I>(
        &'a self,
        x: usize,
        y: usize,
        it: I,
    ) -> impl Iterator<Item = (usize, usize)> + 'a
    where
        I: Iterator<Item = (usize, usize)> + 'a,
    {
        it.map(move |p| (x.wrapping_add(p.0), y.wrapping_add(p.1)))
            .filter(|p| p.0 < self.h && p.1 < self.w)
    }
}

// ---------- 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 ----------
// ---------- begin transpose ----------
pub fn transpose<T>(a: Vec<Vec<T>>) -> Vec<Vec<T>> {
    if a.is_empty() {
        return a;
    }
    let h = a.len();
    let w = a[0].len();
    assert!(a.iter().all(|a| a.len() == w));
    let mut ta: Vec<_> = (0..w).map(|_| Vec::with_capacity(h)).collect();
    for a in a {
        for (ta, a) in ta.iter_mut().zip(a) {
            ta.push(a);
        }
    }
    ta
}
// ---------- end transpose ----------