Submission #361248

#	Time	Username	Problem	Language	Result	Execution time	Memory
361248		HoneyBadger	Olympic Bus (JOI20_ho_t4)	C++17	16 / 100	75 ms	6976 KiB

ho_t4

#include <iostream>
#include <iomanip>
#include <cstdio>
#include <vector>
#include <bitset>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <utility>
#include <algorithm>
#include <random>
#include <cmath>
#include <cassert>
#include <climits>
#include <ctime>
#include <chrono>


/*
#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx,avx2,tune=native")
*/


#ifdef LOCAL
    #define dbg(x) cout << #x << " : " << x << endl;
#else
    #define dbg(x)
#endif

#define int long long
#define pb push_back
#define ppb pop_back()
#define mp make_pair
#define fi(a, b) for (int i = a; i < b; i++)
#define fj(a, b) for (int j = a; j < b; j++)
#define fk(a, b) for (int k = a; k < b; k++)
#define fi1(a, b) for (int i = a - 1; i >= b; i--)
#define fj1(a, b) for (int j = a - 1; j >= b; j--)
#define fk1(a, b) for (int k = a - 1; k >= b; k--)
#define fx(x, a) for (auto& x : a)
#define rep(i, a, b) for (int i = a; i < b; ++i)
#define rep1(i, a, b) for (int i = a - 1; i >= b; --i)
#define siz(x) (int)x.size()
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()

using namespace std;

template<typename T1, typename T2>inline void mine(T1 &x, const T2 &y) { if (y < x) x = y; }
template<typename T1, typename T2>inline void maxe(T1 &x, const T2 &y) { if (x < y) x = y; }

ostream& operator << (ostream &out, const vector<int> &b) {
    for (auto k : b) out << k << ' ';
    return out;
}

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef char ch;
typedef string str;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef vector<vpii> vvpii;
typedef vector<ch> vch;
typedef vector<vch> vvch;
typedef vector<str> vs;



const int MOD = 1000000007;
const int INF = 1000000050;
const long long BIG = (long long)2e18 + 50;
const int MX = 200010;
const double EPS = 1e-9;


mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n, m;
int c[MX];
int from[MX];
int to[MX];

vi bandij(int s, int ban, const vvi &g) {
	vi dist(n, BIG);
	vch used(n, 0);
	dist[s] = 0;
	for (int i = 0; i < n - 1; ++i) {
		int v = -1;
		for (int j = 0; j < n; ++j) {
			if (!used[j] && (v == -1 || dist[j] < dist[v])) {
				v = j;
			}
		}
		if (dist[v] == BIG) break;
		fx(id, g[v]) {
			if (id == ban) continue;
			mine(dist[to[id]], dist[v] + c[id]);	
		}
		used[v] = 1;
	}
	return dist;
}

pair<vvi, vi> dij(int s, const vvi & g) {
	vi dist(n, BIG);
	vch used(n, 0);
	vvpii gb(n);
	dist[s] = 0;
	for (int i = 0; i < n - 1; ++i) {
		int v = -1;
		for (int j = 0; j < n; ++j) {
			if (!used[j] && (v == -1 || dist[j] < dist[v])) {
				v = j;
			}
		}
		if (dist[v] == BIG) break;
		fx(id, g[v]) {
			if (dist[to[id]] > dist[v] + c[id]) {
				gb[to[id]].clear();
				dist[to[id]] = dist[v] + c[id];
			}
			if (dist[to[id]] == dist[v] + c[id])
				gb[to[id]].pb({from[id], id});
		}
		used[v] = 1;
	}
	vvpii gb2(n);
	for (int i = 0; i < n; ++i) {
		used[i] = 0;
		for (auto[x, id] : gb[i]) {
			gb2[x].pb({i, id});
		}
	}
	swap(gb2, gb);
	vi ord;
	function<void(int)> dfs = [&](int v) {
		used[v] = 1;
		for (auto[x, id] : gb[v]) {
			if (!used[x]) {
				dfs(x);
			}
		}
		ord.pb(v);
	};	
	dfs(s);
	reverse(all(ord));
	vector<pair<ull, int>> ways(n, {0, 0});
	ways[s] = {1, 1};
	fx(v, ord) {
		ways[v].second %= MOD;
		for (auto[x, id] : gb[v]) {
			ways[x].first += ways[v].first;
			ways[x].second += ways[v].second; 
		}
	}
	vi bridges;
	fx(v, ord) {
		for (auto[to, id] : gb[v]) {
			if (ways[to] == ways[v]) {
				bridges.pb(id);
			}
		}
	}
	sort(all(bridges));
	vvi dists;
	fx(id, bridges) 
		dists.pb(bandij(s, id, g));
	dists.pb(dist);
	fx(x, bridges)
		x %= m;
	return mp(dists, bridges);
}


int d[MX];

int get(vi &bridges, int id) {
	auto it = lb(all(bridges), id);
	if (it == bridges.end() || *it != id)
		return bridges.size();
	return it - bridges.begin();
}

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

   
    cin >> n >> m;
    vvi g(n);
    vvi gc(n);
    for (int i = 0; i < m; ++i) {
    	cin >> from[i] >> to[i] >> c[i] >> d[i];
    	--from[i], --to[i];
    	from[i + m] = to[i];
    	to[i + m] = from[i];
    	c[i + m] = c[i];
    	g[from[i]].pb(i);
    	gc[from[i + m]].pb(i + m);
	}
	const int s = 0;
	const int t = n - 1;
	auto[dsv, bsv] = dij(s, g);
	auto[dvs, bvs] = dij(s, gc);
	auto[dtv, btv] = dij(t, g);
	auto[dvt, bvt] = dij(t, gc);
	
	int ans = dsv.back()[t] + dtv.back()[s];
	for (int id = 0; id < m; ++id) {
	
		int u = from[id];
		int v = to[id];
		
		int bid = get(bsv, id);
		int st = dsv[bid][t];
		int sv = dsv[bid][v];
		bid = get(bvs, id);
		int us = dvs[bid][u];
		bid = get(btv, id);
		int ts = dtv[bid][s];
		int tv = dtv[bid][v];
		bid = get(bvt, id);
		int ut = dvt[bid][u];

		int cur = d[id];
		cur += min(st, sv + c[id] + ut);
		cur += min(ts, tv + c[id] + us);
		mine(ans, cur);
	}
	cout << (ans >= BIG ? -1 : ans) << '\n';
}	

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 63