結果

問題 No.160 最短経路のうち辞書順最小
コンテスト
ユーザー negnat
提出日時 2022-03-02 03:31:58
言語 Rust
(1.83.0 + proconio)
結果
AC  
実行時間 8 ms / 5,000 ms
コード長 4,281 bytes
コンパイル時間 16,428 ms
コンパイル使用メモリ 378,060 KB
実行使用メモリ 5,376 KB
最終ジャッジ日時 2024-07-08 11:08:03
合計ジャッジ時間 14,261 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge3
このコードへのチャレンジ
（要ログイン）
ファイルパターン 結果
sample AC * 4
other AC * 26
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: `min`
 --> src/main.rs:2:16
  |
2 | use std::cmp::{min, Ordering, Reverse};
  |                ^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: variable does not need to be mutable
   --> src/main.rs:132:17
    |
132 |             let mut prev = Node { id: e.to, cost: node.cost + e.cost, next: Some(node.id) };
    |                 ----^^^^
    |                 |
    |                 help: remove this `mut`
    |
    = note: `#[warn(unused_mut)]` on by default

ソースコード

diff # 

use std::collections::binary_heap::BinaryHeap;
use std::cmp::{min, Ordering, Reverse};

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($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),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

#[derive(Debug, Clone, Copy)]
struct Edge {
    to: usize,
    cost: i32,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Node {
    id: usize,
    cost: i32,
    next: Option<usize>,
}

#[derive(Debug)]
struct Graph {
    nodes: Vec<Node>,
    edges: Vec<Vec<Edge>>,
}

impl Graph {
    fn new(n_nodes: usize) -> Self {
        let mut nodes = Vec::with_capacity(n_nodes);
        let edges = vec![Vec::new(); n_nodes];

        for i in 0..n_nodes {
            nodes.push(Node { id: i, cost: i32::MAX, next: None })
        }

        Self {
            nodes,
            edges,
        }
    }

    fn add_edge(&mut self, from: usize, to: usize, cost: i32) {
        self.edges[from].push(Edge { to, cost });
        self.edges[to].push(Edge { to: from, cost });
    }
}

impl PartialOrd<Self> for Node {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        match (self.next, other.next) {
            (Some(sn), Some(on)) => { (self.cost, sn).partial_cmp(&(other.cost, on)) }
            (_, _) => { self.cost.partial_cmp(&other.cost) }
        }
    }
}

impl Ord for Node {
    fn cmp(&self, other: &Self) -> Ordering {
        match (self.next, other.next) {
            (Some(sn), Some(on)) => { (self.cost, sn).cmp(&(other.cost, on)) }
            (_, _) => { self.cost.cmp(&other.cost) }
        }
    }
}

fn dijkstra(graph: &mut Graph, from: usize, to: usize) {
    let mut heap = BinaryHeap::new();

    heap.push(Reverse(Node { id: to, cost: 0, next: None }));

    while let Some(Reverse(node)) = heap.pop() {
        if graph.nodes[node.id] < node {
            continue;
        }

        graph.nodes[node.id] = node;

        if node.id == from {
            break;
        }

        for e in &graph.edges[node.id] {
            let mut prev = Node { id: e.to, cost: node.cost + e.cost, next: Some(node.id) };

            if prev < graph.nodes[e.to] {
                graph.nodes[e.to] = prev;
                heap.push(Reverse(prev));
            }
        }
    }
}

fn trace_path(graph: &Graph, from: usize) -> Vec<&Node> {
    let mut path = Vec::new();
    let mut node_id = from;

    loop {
        let node = &graph.nodes[node_id];
        path.push(node);

        if let Some(next_node_id) = node.next {
            node_id = next_node_id;
        } else {
            break;
        }
    }

    path
}

fn main() {
    input! {
        n: usize,
        m: usize,
        s: usize,
        g: usize,
        edges: [(usize, usize, i32); m]
    }

    let mut graph = Graph::new(n);

    for (from, to, cost) in edges {
        graph.add_edge(from, to, cost);
    }

    dijkstra(&mut graph, s, g);
    let path = trace_path(&graph, s);
    let answer = path.iter().map(|p| p.id.to_string()).collect::<Vec<_>>().join(" ");

    println!("{}", answer);
}
0