Submission #2215045

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Source Code Expand

/**
*  _           _                 __                            _   _ _   _                                 _                    _                  _
* | |         | |               / /                           | | (_) | (_)                               | |                  (_)                | |
* | |__   __ _| |_ ___   ___   / /__ ___  _ __ ___  _ __   ___| |_ _| |_ ___   _____ ______ _ __ _   _ ___| |_ ______ ___ _ __  _ _ __  _ __   ___| |_ ___
* | '_ \ / _` | __/ _ \ / _ \ / / __/ _ \| '_ ` _ \| '_ \ / _ \ __| | __| \ \ / / _ \______| '__| | | / __| __|______/ __| '_ \| | '_ \| '_ \ / _ \ __/ __|
* | | | | (_| | || (_) | (_) / / (_| (_) | | | | | | |_) |  __/ |_| | |_| |\ V /  __/      | |  | |_| \__ \ |_       \__ \ | | | | |_) | |_) |  __/ |_\__ \
* |_| |_|\__,_|\__\___/ \___/_/ \___\___/|_| |_| |_| .__/ \___|\__|_|\__|_| \_/ \___|      |_|   \__,_|___/\__|      |___/_| |_|_| .__/| .__/ \___|\__|___/
*                                                  | |                                                                           | |   | |
*                                                  |_|                                                                           |_|   |_|
*
* 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::iter::FromIterator;
#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};
mod util {
    use std::io::{stdin, stdout, BufWriter, StdoutLock};
    use std::str::FromStr;
    use std::fmt::Debug;
    #[allow(dead_code)]
    pub fn line() -> String {
        let mut line: String = String::new();
        stdin().read_line(&mut line).unwrap();
        line.trim().to_string()
    }
    #[allow(dead_code)]
    pub fn chars() -> Vec<char> {
        line().chars().collect()
    }
    #[allow(dead_code)]
    pub fn gets<T: FromStr>() -> Vec<T>
    where
        <T as FromStr>::Err: Debug,
    {
        let mut line: String = String::new();
        stdin().read_line(&mut line).unwrap();
        line.split_whitespace()
            .map(|t| t.parse().unwrap())
            .collect()
    }
    #[allow(dead_code)]
    pub fn with_bufwriter<F: FnOnce(BufWriter<StdoutLock>) -> ()>(f: F) {
        let out = stdout();
        let writer = BufWriter::new(out.lock());
        f(writer)
    }
}
#[allow(unused_macros)]
macro_rules ! get { ( $ t : ty ) => { { let mut line : String = String :: new ( ) ; stdin ( ) . read_line ( & mut line ) . unwrap ( ) ; line . trim ( ) . parse ::<$ t > ( ) . unwrap ( ) } } ; ( $ ( $ t : ty ) ,* ) => { { let mut line : String = String :: new ( ) ; stdin ( ) . read_line ( & mut line ) . unwrap ( ) ; let mut iter = line . split_whitespace ( ) ; ( $ ( iter . next ( ) . unwrap ( ) . parse ::<$ t > ( ) . unwrap ( ) , ) * ) } } ; ( $ t : ty ; $ n : expr ) => { ( 0 ..$ n ) . map ( | _ | get ! ( $ t ) ) . collect ::< Vec < _ >> ( ) } ; ( $ ( $ t : ty ) ,*; $ n : expr ) => { ( 0 ..$ n ) . map ( | _ | get ! ( $ ( $ t ) ,* ) ) . collect ::< Vec < _ >> ( ) } ; ( $ t : ty ;; ) => { { let mut line : String = String :: new ( ) ; stdin ( ) . read_line ( & mut line ) . unwrap ( ) ; line . split_whitespace ( ) . map ( | t | t . parse ::<$ t > ( ) . unwrap ( ) ) . collect ::< Vec < _ >> ( ) } } ; ( $ t : ty ;; $ n : expr ) => { ( 0 ..$ n ) . map ( | _ | get ! ( $ t ;; ) ) . collect ::< Vec < _ >> ( ) } ; }
#[allow(unused_macros)]
macro_rules ! debug { ( $ ( $ a : expr ) ,* ) => { println ! ( concat ! ( $ ( stringify ! ( $ a ) , " = {:?}, " ) ,* ) , $ ( $ a ) ,* ) ; } }
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();
    }
}

#[allow(dead_code)]
/// Union Find Tree
pub struct UFT {
    pub par: Vec<usize>,
    pub rank: Vec<usize>,
}
impl UFT {
    #[allow(dead_code)]
    pub fn new(n: usize) -> Self {
        UFT {
            par: (0..n).collect(),
            rank: vec![0; n],
        }
    }
    #[allow(dead_code)]
    pub fn root(&mut self, x: usize) -> usize {
        if self.par[x] == x {
            x
        } else {
            let p = self.par[x];
            let pp = self.root(p);
            self.par[x] = pp;
            pp
        }
    }
    #[allow(dead_code)]
    pub fn merge(&mut self, x: usize, y: usize) {
        let x = self.root(x);
        let y = self.root(y);
        if x == y {
            return;
        }
        if self.rank[x] < self.rank[y] {
            self.par[x] = y;
        } else {
            self.par[y] = x;
            if self.rank[x] == self.rank[y] {
                self.rank[x] += 1;
            }
        }
    }
}

#[derive(Eq, PartialEq, Clone, Debug)]
/// Equivalent to std::cmp::Reverse
pub struct Rev<T>(pub T);
impl<T: PartialOrd> PartialOrd for Rev<T> {
    fn partial_cmp(&self, other: &Rev<T>) -> Option<Ordering> {
        other.0.partial_cmp(&self.0)
    }
}
impl<T: Ord> Ord for Rev<T> {
    fn cmp(&self, other: &Rev<T>) -> Ordering {
        other.0.cmp(&self.0)
    }
}

fn solve() {
    let (n, m) = get!(usize, usize);
    let ftc = get!(usize, usize, u64; m);
    let q = get!(usize);
    let ab = get!(usize, usize; q);

    let mut g = vec![vec![None; n]; n];

    for (f, t, c) in ftc {
        g[f][t] = Some(c);
        g[t][f] = Some(c);
    }

    let mut uft = UFT::new(n);
    let mut ee = vec![Vec::new(); n];

    for (a, b) in ab {
        let ra = uft.root(a);
        let rb = uft.root(b);

        let mut es = Vec::new();

        es.append(&mut ee[ra]);
        es.append(&mut ee[rb]);

        let mut va = Vec::new();
        let mut vb = Vec::new();

        for i in 0..n {
            if uft.root(i) == ra {
                va.push(i);
            }
            if uft.root(i) == rb {
                vb.push(i);
            }
        }

        let total_v = va.len() + vb.len();

        for &aa in &va {
            for &bb in &vb {
                if let Some(c) = g[aa][bb] {
                    es.push(((aa, bb), c));
                }
            }
        }
        let mut kruskal = UFT::new(n);
        uft.merge(a, b);
        let root = uft.root(a);

        es.sort_by_key(|t| t.1);
        let mut ans = 0;

        for ((f, t), c) in es {
            if kruskal.root(f) != kruskal.root(t) {
                kruskal.merge(f, t);
                ans += c;
                ee[root].push(((f, t), c));
            }
        }

        if ee[root].len() + 1 == total_v {
            println!("{}", ans);
        } else {
            println!("IMPOSSIBLE");
        }
    }
}

Submission Info

Judge Result