Submission #678618

#	Time	Username	Problem	Language	Result	Execution time	Memory
678618		SanguineChameleon	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	274 ms	20416 KiB

commuter_pass

// BEGIN BOILERPLATE CODE

#include <bits/stdc++.h>
using namespace std;

#ifdef KAMIRULEZ
	const bool kami_loc = true;
	const long long kami_seed = 69420;
#else
	const bool kami_loc = false;
	const long long kami_seed = chrono::steady_clock::now().time_since_epoch().count();
#endif

const string kami_fi = "kamirulez.inp";
const string kami_fo = "kamirulez.out";
mt19937_64 kami_gen(kami_seed);

long long rand_range(long long rmin, long long rmax) {
	uniform_int_distribution<long long> rdist(rmin, rmax);
	return rdist(kami_gen);
}

long double rand_real(long double rmin, long double rmax) {
	uniform_real_distribution<long double> rdist(rmin, rmax);
	return rdist(kami_gen);
}

void file_io(string fi, string fo) {
	if (fi != "" && (!kami_loc || fi == kami_fi)) {
		freopen(fi.c_str(), "r", stdin);
	}
	if (fo != "" && (!kami_loc || fo == kami_fo)) {
		freopen(fo.c_str(), "w", stdout);
	}
}

void set_up() {
	if (kami_loc) {
		file_io(kami_fi, kami_fo);
	}
	ios_base::sync_with_stdio(0);
	cin.tie(0);
}

void just_do_it();

void just_exec_it() {
	if (kami_loc) {
		auto pstart = chrono::steady_clock::now();
		just_do_it();
		auto pend = chrono::steady_clock::now();
		long long ptime = chrono::duration_cast<chrono::milliseconds>(pend - pstart).count();
		string bar(50, '=');
		cout << '\n' << bar << '\n';
		cout << "Time: " << ptime << " ms" << '\n';
	}
	else {
		just_do_it();
	}
}

int main() {
	set_up();
	just_exec_it();
	return 0;
}

// END BOILERPLATE CODE

// BEGIN MAIN CODE

const long long inf = 1e18L + 20;
const int ms = 1e5 + 20;
vector<pair<int, int>> adj[ms];
long long d_sx[ms];
long long d_tx[ms];
long long d_ty[ms];
long long dp_tx[ms];
long long dp_ty[ms];
bool g1[ms];
bool g2[ms];
bool g3[ms];
bool f[ms];
int n, m, sx, sy, tx, ty;

void dijk(int cx, long long d[]) {
	for (int i = 1; i <= n; i++) {
		d[i] = inf;
	}
	d[cx] = 0;
	priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> q;
	q.push({0, cx});
	while (!q.empty()) {
		int u = q.top().second;
		long long cd = q.top().first;
		q.pop();
		if (d[u] != cd) {
			continue;
		}
		for (auto x: adj[u]) {
			int v = x.first;
			int w = x.second;
			if (d[u] + w < d[v]) {
				d[v] = d[u] + w;
				q.push({d[v], v});
			} 
		}
	}
}

void dfs1(int u) {
	if (u == sy) {
		f[u] = true;
		return;
	}
	for (auto x: adj[u]) {
		int v = x.first;
		int w = x.second;
		if (d_sx[u] + w == d_sx[v]) {
			if (!g3[v]) {
				dfs1(v);
				g3[v] = true;
			}
			f[u] |= f[v];
		}
	}
}

void dfs2(int u, long long dp[], long long d[], bool g[]) {
	dp[u] = d[u];
	if (u == sy) {
		return;
	}
	for (auto x: adj[u]) {
		int v = x.first;
		int w = x.second;
		if (d_sx[u] + w == d_sx[v]) {
			if (f[v]) {
				if (!g[v]) {
					dfs2(v, dp, d, g);
					g[v] = true;
				}
				dp[u] = min(dp[u], dp[v]);
			}
		}
	}
}

void just_do_it() {
	cin >> n >> m;
	cin >> sx >> sy >> tx >> ty;
	for (int i = 0; i < m; i++) {
		int u, v, w;
		cin >> u >> v >> w;
		adj[u].push_back({v, w});
		adj[v].push_back({u, w});
	}
	dijk(sx, d_sx);
	dijk(tx, d_tx);
	dijk(ty, d_ty);
	dfs1(sx);
	dfs2(sx, dp_tx, d_tx, g1);
	dfs2(sx, dp_ty, d_ty, g2);
	long long res = d_tx[ty];
	for (int u = 1; u <= n; u++) {
		if (f[u]) {
			res = min(res, dp_tx[u] + d_ty[u]);
			res = min(res, dp_ty[u] + d_tx[u]);
		}
	}
	cout << res;
}

// END MAIN CODE

Compilation message (stderr)

commuter_pass.cpp: In function 'void file_io(std::string, std::string)':
commuter_pass.cpp:30:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |   freopen(fi.c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:33:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |   freopen(fo.c_str(), "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45