Problem:
Score : 400 points

Problem Statement

There are N towns in the State of Atcoder, connected by M bidirectional roads.

The i-th road connects Town A_i and B_i and has a length of C_i.

Joisino is visiting R towns in the state, r_1,r_2,..,r_R (not necessarily in this order).

She will fly to the first town she visits, and fly back from the last town she visits, but for the rest of the trip she will have to travel by road.

If she visits the towns in the order that minimizes the distance traveled by road, what will that distance be?

Constraints

2≤N≤200

1≤M≤N×(N-1)/2

2≤R≤min(8,N) (min(8,N) is the smaller of 8 and N.)

r_i≠r_j (i≠j)

1≤A_i,B_i≤N, A_i≠B_i

(A_i,B_i)≠(A_j,B_j),(A_i,B_i)≠(B_j,A_j) (i≠j)

1≤C_i≤100000

Every town can be reached from every town by road.

All input values are integers.

Input

Input is given from Standard Input in the following format:

N M R
r_1 ... r_R
A_1 B_1 C_1
:
A_M B_M C_M

Output

Print the distance traveled by road if Joisino visits the towns in the order that minimizes it.

Sample Input 1

3 3 3
1 2 3
1 2 1
2 3 1
3 1 4

Sample Output 1

2

For example, if she visits the towns in the order of 1, 2, 3, the distance traveled will be 2, which is the minimum possible.

Sample Input 2

3 3 2
1 3
2 3 2
1 3 6
1 2 2

Sample Output 2

4

The shortest distance between Towns 1 and 3 is 4. Thus, whether she visits Town 1 or 3 first, the distance traveled will be 4.

Sample Input 3

4 6 3
2 3 4
1 2 4
2 3 3
4 3 1
1 4 1
4 2 2
3 1 6

Sample Output 3

3

Solution in Rust (1.42.0) (judge verdict: Accepted)

// -*- coding:utf-8-unix -*-

extern crate lazy_static;
extern crate num_bigint;
// 0.2.2
extern crate num_traits;

// 0.2.8
use num_bigint::BigInt;
use num_traits::{one, zero, Num, NumAssignOps, NumOps, One, Pow, Zero};

// use proconio::derive_readable;
use proconio::fastout;
use proconio::input;
// use std::convert::TryInto;
use itertools::{assert_equal, concat, Itertools};
use lazy_static::lazy_static;
// use libm::*;
use std::cmp::*;
use std::collections::{BinaryHeap, HashMap, HashSet, VecDeque};
use std::io::*;
use std::mem::swap;
use std::ops::{BitAnd, Range, ShrAssign};
use std::str::FromStr;
use std::sync::Mutex;
use superslice::*;
use std::env::current_exe;

// ##########
// read
// ###########
pub fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

// ##########
// chmin, chmax
// https://qiita.com/maguro_tuna/items/fab200fdc1efde1612e7
// ###########

#[allow(unused_macros)]
macro_rules! chmin {
    ($base:expr, $($cmps:expr),+ $(,)*) => {{
        let cmp_min = min!($($cmps),+);
        if $base > cmp_min {
            $base = cmp_min;
            true
        } else {
            false
        }
    }};
}

#[allow(unused_macros)]
macro_rules! chmax {
    ($base:expr, $($cmps:expr),+ $(,)*) => {{
        let cmp_max = max!($($cmps),+);
        if $base < cmp_max {
            $base = cmp_max;
            true
        } else {
            false
        }
    }};
}

#[allow(unused_macros)]
macro_rules! min {
    ($a:expr $(,)*) => {{
        $a
    }};
    ($a:expr, $b:expr $(,)*) => {{
        std::cmp::min($a, $b)
    }};
    ($a:expr, $($rest:expr),+ $(,)*) => {{
        std::cmp::min($a, min!($($rest),+))
    }};
}

#[allow(unused_macros)]
macro_rules! max {
    ($a:expr $(,)*) => {{
        $a
    }};
    ($a:expr, $b:expr $(,)*) => {{
        std::cmp::max($a, $b)
    }};
    ($a:expr, $($rest:expr),+ $(,)*) => {{
        std::cmp::max($a, max!($($rest),+))
    }};
}



// ##########
// modint
// https://qiita.com/drken/items/3b4fdf0a78e7a138cd9a
// ##########

#[allow(dead_code)]
fn modinv<T: Num + NumAssignOps + NumOps + Copy + PartialOrd>(a: T, m: T) -> T {
    let mut a = a;
    let mut b = m;
    let mut u: T = one();
    let mut v: T = zero();

    while b != zero() {
        let t = a / b;
        a -= t * b;
        swap(&mut a, &mut b);
        u -= t * v;
        swap(&mut u, &mut v);
    }
    u %= m;
    if u < zero() {
        u += m;
    }
    return u;
}

#[test]
fn modinv_test() {
    assert_eq!(1, modinv(1, 13));
    assert_eq!(2, modinv(7, 13));
    assert_eq!(3, modinv(9, 13));
    assert_eq!(4, modinv(10, 13));
    assert_eq!(5, modinv(8, 13));
}

// long long modpow(long long a, long long n, long long mod) {
// long long res = 1;
// while (n > 0) {
// if (n & 1) res = res * a % mod;
// a = a * a % mod;
// n >>= 1;
// }
// return res;
// }
#[allow(dead_code)]
fn modpow<T>(a: T, n: T, modulo: T) -> T
where
    T: Num + NumAssignOps + NumOps + Copy + PartialOrd + BitAnd + PartialEq + ShrAssign,
    <T as BitAnd>::Output: PartialEq + Num,
{
    let mut res = one();
    let mut a = a;
    let mut n = n;
    while n > zero() {
        if (n & one()) == one() {
            res = res * a % modulo;
        }
        a = a * a % modulo;
        n >>= one();
    }

    return res;
}

#[test]
fn modpow_test() {
    assert_eq!(4, modpow(2, 2, 13));
    assert_eq!(3, modpow(2, 4, 13));
}

// 前処理 com_init(): O(n)
// クエリ処理 COM(n, k): O(1)
// conv::com_init();
// conv::com(n,k);
mod comb {
    use super::*;
    lazy_static! {
        static ref FAC: Mutex<Vec<usize>> = Mutex::default();
        static ref FINV: Mutex<Vec<usize>> = Mutex::default();
        static ref INV: Mutex<Vec<usize>> = Mutex::default();
        static ref MODULO: Mutex<usize> = Mutex::default();
        // static ref MAXNCONV: Mutex<usize> = Mutex::default();
    }

    // // テーブルを作る前処理
    // void com_init() {
    // fac[0] = fac[1] = 1;
    // finv[0] = finv[1] = 1;
    // inv[1] = 1;
    // for (int i = 2; i < MAX; i++){
    // fac[i] = fac[i - 1] * i % MOD;
    // inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
    // finv[i] = finv[i - 1] * inv[i] % MOD;
    // }

    #[allow(dead_code)]
    fn com_init_with(modulo: usize, maxn_conv: usize) {
        let mut fac = FAC.lock().unwrap();
        let mut finv = FINV.lock().unwrap();
        let mut inv = INV.lock().unwrap();
        *fac = vec![0; maxn_conv];
        *finv = vec![0; maxn_conv];
        *inv = vec![0; maxn_conv];

        let mut g_modulo = MODULO.lock().unwrap();
        *g_modulo = modulo;

        fac[0] = 1;
        fac[1] = 1;
        finv[0] = 1;
        finv[1] = 1;
        inv[1] = 1;

        for i in 2..maxn_conv {
            fac[i] = fac[i - 1] * i % modulo;
            inv[i] = modulo - inv[modulo % i] * (modulo / i) % modulo;
            finv[i] = finv[i - 1] * inv[i] % modulo;
        }
    }

    #[allow(dead_code)]
    pub fn com_init() {
        com_init_with(MOD, MAXN_CONV);
    }

    // // 二項係数計算
    // long long COM(int n, int k){
    // if (n < k) return 0;
    // if (n < 0 || k < 0) return 0;
    // return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
    // }
    #[allow(dead_code)]
    pub fn com(n: usize, k: usize) -> usize {
        let fac = FAC.lock().unwrap();
        let finv = FINV.lock().unwrap();
        // let mut inv = INV.lock().unwrap();
        let m = *MODULO.lock().unwrap();

        if n < k {
            return 0;
        }
        // if n < 0 || k < 0 {
        //     return 0;
        // }
        return fac[n] * (finv[k] * finv[n - k] % m) % m;
    }

    #[test]
    fn com_test() {
        com_init_with(13, 100);
        assert_eq!(12, com(12, 1));
        assert_eq!(66 % 13, com(12, 2));
        assert_eq!(220 % 13, com(12, 3));
        assert_eq!(495 % 13, com(12, 4));
        assert_eq!(792 % 13, com(12, 5));
        assert_eq!(924 % 13, com(12, 6));
        assert_eq!(com(12, 5), com(12, 7));
    }
}

// ##########
// union-find
// http://sntea.hatenablog.com/entry/2017/06/07/091246
// ##########

mod uf {
    // let mut uf = uf::UnionFind::new(10);
    // uf.unite; uf.same
    #[allow(dead_code)]
    #[derive(Debug)]
    pub struct UnionFind {
    par: Vec<i64>,
        rank: Vec<usize>,
    }

    impl UnionFind {
        #[allow(dead_code)]
        pub fn new(n: usize) -> UnionFind {
            let mut vec = vec![0; n];
            for i in 0..n {
                vec[i] = -1;
            }
            UnionFind {
                par: vec,
                rank: vec![0; n],
            }
        }

        #[allow(dead_code)]
        fn find(&mut self, x: usize) -> usize {
            if self.par[x] < 0 {
                x
            } else {
                let par = self.par[x];
                let res = self.find(par as usize);
                self.par[x] = res as i64;
                res
            }
        }

        #[allow(dead_code)]
        pub fn same(&mut self, a: usize, b: usize) -> bool {
            self.find(a) == self.find(b)
        }

        #[allow(dead_code)]
        pub fn unite(&mut self, a: usize, b: usize) {
            let apar = self.find(a);
            let bpar = self.find(b);
            if self.rank[apar] > self.rank[bpar] {
                self.par[apar] += self.par[bpar];
                self.par[bpar] = apar as i64;
            } else {
                self.par[bpar] += self.par[apar];
                self.par[apar] = bpar as i64;
                if self.rank[apar] == self.rank[bpar] {
                    self.rank[bpar] += 1;
                }
            }
        }

        #[allow(dead_code)]
        pub fn size(&mut self, x: usize) -> usize {
            let parent = self.find(x);
            //parentのparにサイズが負の状態で入る
            return (-self.par[parent]) as usize;
        }
    }

    #[test]
    fn union_find_test() {
        let mut uf = UnionFind::new(10);

        for i in 0..10 {
            for j in 0..10 {
                assert_eq!(i == j, uf.same(i, j));
            }
        }

        uf.unite(0, 1);
        assert_eq!(true, uf.same(0, 1));
        //false
        assert_eq!(false, uf.same(0, 9));
        assert_eq!(false, uf.same(1, 9));
        assert_eq!(false, uf.same(2, 9));

        assert_eq!(2, uf.size(0));
        assert_eq!(2, uf.size(1));
        //1
        assert_eq!(1, uf.size(2));
        assert_eq!(1, uf.size(8));
        assert_eq!(1, uf.size(9));

        uf.unite(8, 9);
        assert_eq!(true, uf.same(0, 1));
        assert_eq!(true, uf.same(8, 9));
        //false
        assert_eq!(false, uf.same(0, 9));
        assert_eq!(false, uf.same(1, 9));
        assert_eq!(false, uf.same(2, 9));

        assert_eq!(2, uf.size(0));
        assert_eq!(2, uf.size(1));
        assert_eq!(2, uf.size(8));
        assert_eq!(2, uf.size(9));
        //1
        assert_eq!(1, uf.size(2));

        uf.unite(1, 9);
        assert_eq!(true, uf.same(0, 1));
        assert_eq!(true, uf.same(8, 9));
        assert_eq!(true, uf.same(0, 8));
        assert_eq!(true, uf.same(0, 9));
        assert_eq!(true, uf.same(1, 8));
        assert_eq!(true, uf.same(1, 9));
        //false
        assert_eq!(false, uf.same(2, 9));

        assert_eq!(4, uf.size(0));
        assert_eq!(4, uf.size(1));
        assert_eq!(4, uf.size(8));
        assert_eq!(4, uf.size(9));
        //1
        assert_eq!(1, uf.size(2));
    }
}

// ###########
// seg_tree
// ant_book
// ###########
mod seg_tree {
    #[derive(Debug)]
    struct SegTree<T: Clone> {
        n: usize,
        dat: Vec<Option<T>>,
    }

    impl<T: Clone + std::fmt::Debug> SegTree<T> {
        #[allow(dead_code)]
        pub fn new(size: usize) -> SegTree<T> {
            let mut size_pow2 = 1;
            while size_pow2 < size {
                size_pow2 *= 2;
            }

            let dat: Vec<Option<T>> = vec![None; 2 * size_pow2 - 1];
            SegTree { n: size_pow2, dat }
        }

        #[allow(dead_code)]
        pub fn update<F: Fn(&Option<T>, &Option<T>) -> Option<T>>(
            &mut self,
            k: usize,
            a: T,
            update: F,
        ) {
            let mut k = k;
            k += self.n - 1;
            self.dat[k] = Some(a);
            while k > 0 {
                k = (k - 1) / 2;
                self.dat[k] = update(&self.dat[k * 2 + 1], &self.dat[k * 2 + 2]);
            }
        }

        #[allow(dead_code)]
        fn query_inner<F: Fn(&Option<T>, &Option<T>) -> Option<T>>(
            &self,
            selection_query: &F,
            a: usize,
            b: usize,
            k: usize,
            l: usize,
            r: usize,
        ) -> Option<T> {
            if r <= a || b <= l {
                // eprintln!("{}, {}, {}, {}, {:?}", a, b, l, r, "none");
                return None;
            }

            return if a <= l && r <= b {
                // eprintln!("{}, {}, {}, {}, {:?}", a, b, r, l, self.dat[k]);
                self.dat[k].clone()
            } else {
                let vl = self.query_inner(selection_query, a, b, k * 2 + 1, l, (l + r) / 2);
                let vr = self.query_inner(selection_query, a, b, k * 2 + 2, (l + r) / 2, r);

                selection_query(&vl, &vr)
            };
        }

        #[allow(dead_code)]
        pub fn query<F: Fn(&Option<T>, &Option<T>) -> Option<T>>(
            &self,
            selection_query: &F,
            a: usize,
            b: usize,
        ) -> Option<T> {
            return self.query_inner(selection_query, a, b, 0, 0, self.n);
        }
    }

    #[test]
    fn test_segtree_rmq() {
        let mut t: SegTree<usize> = SegTree::new(5);

        let cmp_f = |lhs: &Option<usize>, rhs: &Option<usize>| {
            if lhs.is_none() {
                return rhs.clone();
            }

            if rhs.is_none() {
                return lhs.clone();
            }

            return if lhs.unwrap() <= rhs.unwrap() {
                lhs.clone()
            } else {
                rhs.clone()
            };
        };
        // 1, 3, 2, 5, 1
        t.update(0, 1, cmp_f);
        t.update(1, 3, cmp_f);
        t.update(2, 2, cmp_f);
        t.update(3, 5, cmp_f);
        t.update(4, 1, cmp_f);
        // println!("{:?}", t);

        assert_eq!(1, t.query(&cmp_f, 0, 1).unwrap());
        assert_eq!(3, t.query(&cmp_f, 1, 2).unwrap());
        assert_eq!(2, t.query(&cmp_f, 2, 3).unwrap());
        assert_eq!(5, t.query(&cmp_f, 3, 4).unwrap());
        assert_eq!(1, t.query(&cmp_f, 4, 5).unwrap());

        // len2
        assert_eq!(1, t.query(&cmp_f, 0, 2).unwrap());
        assert_eq!(2, t.query(&cmp_f, 1, 3).unwrap());
        assert_eq!(2, t.query(&cmp_f, 2, 4).unwrap());
        assert_eq!(1, t.query(&cmp_f, 3, 5).unwrap());

        // len3
        assert_eq!(1, t.query(&cmp_f, 0, 3).unwrap());
        assert_eq!(2, t.query(&cmp_f, 1, 4).unwrap());
        assert_eq!(1, t.query(&cmp_f, 2, 5).unwrap());

        // len4
        assert_eq!(1, t.query(&cmp_f, 0, 4).unwrap());
        assert_eq!(1, t.query(&cmp_f, 1, 5).unwrap());

        // len5
        assert_eq!(1, t.query(&cmp_f, 0, 6).unwrap());
    }
}

// ##############
// rolling hash
// ###############
mod rolling_hash {
    use super::*;
    use ascii::{AsciiStr, AsciiString};
    use num_traits::AsPrimitive;

    fn contains_with(base: u64, a: &AsciiStr, b: &AsciiStr) -> bool {
        let (al, bl) = (a.len(), b.len());
        if al > bl {
            return false;
        }

        let mut t: u64 = 1;
        for _ in 0..al {
            t = t.wrapping_mul(base);
        }

        let (mut ah, mut bh): (u64, u64) = (0, 0);

        for i in 0..al {
            ah = ah.wrapping_mul(base) + a[i].as_byte() as u64;
        }
        for i in 0..al {
            bh = bh.wrapping_mul(base) + b[i].as_byte() as u64;
        }

        // eprintln!("{}, {}", ah, bh);

        for i in 0..=bl - al {
            if ah == bh {
                return true;
            }
            if i + al < bl {
                let mut add: i64 = b[i + al].as_byte().as_();
                add -= ((b[i].as_byte() as u64).wrapping_mul(t)) as i64;
                bh = (bh.wrapping_mul(base) as i64).wrapping_add(add) as u64;
            }
        }

        return false;
    }

    #[allow(dead_code)]
    pub fn contains(a: &AsciiStr, b: &AsciiStr) -> bool {
        return contains_with(BASE_ROLLING_HASH, a, b);
    }

    #[test]
    fn contains_test() {
        const base: u64 = 1000_000_007;
        assert_eq!(
            false,
            contains_with(
                base,
                &AsciiString::from_str("abc").unwrap(),
                &AsciiString::from_str("a").unwrap()
            )
        );

        assert_eq!(
            true,
            contains_with(
                base,
                &AsciiString::from_str("abc").unwrap(),
                &AsciiString::from_str("aaabca").unwrap()
            )
        );

        assert_eq!(
            true,
            contains_with(
                base,
                &AsciiString::from_str("aaaaaa").unwrap(),
                &AsciiString::from_str("aaaaaa").unwrap()
            )
        );

        assert_eq!(
            false,
            contains_with(
                base,
                &AsciiString::from_str("abc").unwrap(),
                &AsciiString::from_str("aacbaa").unwrap()
            )
        )
    }

    fn overlap_last_and_head_with(base: u64, a: &AsciiStr, b: &AsciiStr) -> usize {
        let (al, bl) = (a.len(), b.len());

        let mut ans = 0;
        let (mut ah, mut bh, mut t): (u64, u64, u64) = (0, 0, 1);
        for i in 1..=min(al, bl) {
            ah = ah.wrapping_add((a[al - i].as_byte() as u64).wrapping_mul(t));
            bh = bh
                .wrapping_mul(base)
                .wrapping_add(b[i - 1].as_byte() as u64);

            if ah == bh {
                ans = i;
            }
            t = t.wrapping_mul(base);
        }

        return ans;
    }

    fn overlap_last_and_head(a: &AsciiStr, b: &AsciiStr) -> usize {
        return overlap_last_and_head_with(BASE_ROLLING_HASH, a, b);
    }

    #[test]
    fn overlap_test() {
        const base: u64 = 1000_000_007;
        assert_eq!(
            0,
            overlap_last_and_head_with(
                base,
                &AsciiString::from_str("abc").unwrap(),
                &AsciiString::from_str("a").unwrap()
            )
        );

        assert_eq!(
            2,
            overlap_last_and_head_with(
                base,
                &AsciiString::from_str("abc").unwrap(),
                &AsciiString::from_str("bca").unwrap()
            )
        );

        assert_eq!(
            5,
            overlap_last_and_head_with(
                base,
                &AsciiString::from_str("hogefoobar").unwrap(),
                &AsciiString::from_str("oobarhoge").unwrap()
            )
        );
    }
}



// ##########
// lazy_static!
// ##########
// lazy_static! {
//     static ref H: Mutex<Vec<i32>> = Mutex::default();
//     static ref W: Mutex<Vec<i32>> = Mutex::default();
// }
// let mut values = VALUES.lock().unwrap();
// values.extend_from_slice(&[1, 2, 3, 4]);
// assert_eq!(&*values, &[1, 2, 3, 4]);

// let mut values = VALUES.lock().unwrap();
// values.extend_from_slice(&[1, 2, 3, 4]);

// MOD, Combination関連に使う定数
#[allow(dead_code)]
const BASE_ROLLING_HASH: u64 = 1158187049;
#[allow(dead_code)]
const MOD: usize = 1000000007;
#[allow(dead_code)]
const MAXN_CONV: usize = 510000;

// abc073-C
// #[fastout]
fn main() {
    input![n: usize, m: usize, r: usize, rs: [usize; r], abc: [(usize, usize, usize); m]];
    //new type

    let mut lens = vec![vec![std::usize::MAX / 100; n]; n];

    for (a,b,c) in abc{
        let a=a-1; let b=b-1;
        lens[a][b] = c;
        lens[b][a] = c;
    }

    for i in 0..n{
        lens[i][i] = 0;
    }

    for k in 0..n {
        for i in 0..n {
            for j in 0..n {
                chmin!(lens[i][j], lens[i][k] + lens[j][k]);
            }
        }
    }

    // eprintln!("{:?}", lens);

    let rs = rs.iter().map(|r| r-1).collect_vec();

    let mut vecs = Vec::new();
    permutations(&mut vecs, Vec::new(), 0, &rs);

    // eprintln!("{:?}", vecs);
    let mut ans = std::usize::MAX / 100;
    for vec in vecs{
        let mut mid = 0;

        for i in 0..rs.len()-1{
            mid += lens[vec[i]][vec[i+1]];
        }

        chmin!(ans, mid);
    }

    println!("{}", ans);
}

fn permutations(vecs: &mut Vec<Vec<usize>>, cur_vec: Vec<usize>, current: usize, rs:& Vec<usize>){
    // eprintln!("{:b}", current);
    if current == 2usize.pow(rs.len() as u32) - 1 {
        vecs.push(cur_vec);
        return;
    }

    for i in 0..rs.len(){
        if current >> i & 1 == 1{
            continue;
        }

        let mut new_vec = cur_vec.clone();
        new_vec.push(rs[i]);
        permutations(vecs, new_vec, current | (1 << i), rs);
    }
}