Submission #924100

#	Time	Username	Problem	Language	Result	Execution time	Memory
924100		TAhmed33	Commuter Pass (JOI18_commuter_pass)	C++98	100 / 100	270 ms	30576 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize ("trapv")
typedef long long ll;
const ll inf = 1e18;
const int MAXN = 1e5 + 25;
vector <pair <ll, ll>> adj[MAXN];
int n, m, s, t, u, v;
vector <int> adj2[MAXN];
ll dist[MAXN], dist2[MAXN];
ll dp[MAXN][2];
ll ans (int pos, int c) {
	ll &ret = dp[pos][c];
	if (ret != -1) return ret;
	if (c == 0) {
		ret = dist[pos] + ans(pos, 1);
		ll mn = inf;
		for (auto j : adj2[pos]) mn = min(mn, ans(j, 0));
		ret = min(ret, mn);
	} else {
		ret = dist2[pos];
		ll mn = inf;
		for (auto j : adj2[pos]) mn = min(mn, ans(j, 1));
		ret = min(ret, mn);
	}
	return ret;
}
ll ans2 (int pos, int c) {
	ll &ret = dp[pos][c];
	if (ret != -1) return ret;
	if (c == 0) {
		ret = dist2[pos] + ans2(pos, 1);
		ll mn = inf;
		for (auto j : adj2[pos]) mn = min(mn, ans2(j, 0));
		ret = min(ret, mn);
	} else {
		ret = dist[pos];
		ll mn = inf;
		for (auto j : adj2[pos]) mn = min(mn, ans2(j, 1));
		ret = min(ret, mn);
	}
	return ret;
}
int main () {
	ios::sync_with_stdio(0); cin.tie(0);
	cin >> n >> m >> s >> t >> u >> v;
	for (int i = 1; i <= m; i++) { 
		int a, b, c;
		cin >> a >> b >> c;
		adj[a].push_back({b, c});
		adj[b].push_back({a, c});
	}
	for (int i = 1; i <= n; i++) dist[i] = inf;
	dist[s] = 0;
	priority_queue <pair <ll, ll>, vector <pair <ll, ll>>, greater <>> pq;
	pq.push({0, s});
	while (!pq.empty()) {
		auto k = pq.top();
		pq.pop();
		if (k.first > dist[k.second]) continue;
		for (auto j : adj[k.second]) {
			if (j.second + k.first < dist[j.first]) {
				dist[j.first] = k.first + j.second;
				pq.push({dist[j.first], j.first});
			}
		}
	}
	for (int i = 1; i <= n; i++) dist2[i] = inf;
	dist2[t] = 0;
	pq.push({0, t});
	while (!pq.empty()) {
		auto k = pq.top();
		pq.pop();
		if (k.first > dist2[k.second]) continue;
		for (auto j : adj[k.second]) {
			if (j.second + k.first < dist2[j.first]) {
				dist2[j.first] = k.first + j.second;
				pq.push({dist2[j.first], j.first});
			}
		}
	}
	for (int i = 1; i <= n; i++) {
		for (auto j : adj[i]) {
			if (dist[i] + j.second == dist[j.first] && dist2[i] == dist2[j.first] + j.second && dist[i] + dist2[j.first] + j.second == dist[t]) {
				adj2[i].push_back(j.first);
			}
		}
	}
	for (int i = 1; i <= n; i++) dist[i] = dist2[i] = inf;
	dist[u] = 0;
	pq.push({0, u});
	while (!pq.empty()) {
		auto k = pq.top();
		pq.pop();
		if (k.first > dist[k.second]) continue;
		for (auto j : adj[k.second]) {
			if (j.second + k.first < dist[j.first]) {
				dist[j.first] = k.first + j.second;
				pq.push({dist[j.first], j.first});
			}
		}
	}
	dist2[v] = 0;
	pq.push({0, v});
	while (!pq.empty()) {
		auto k = pq.top();
		pq.pop();
		if (k.first > dist2[k.second]) continue;
		for (auto j : adj[k.second]) {
			if (j.second + k.first < dist2[j.first]) {
				dist2[j.first] = k.first + j.second;
				pq.push({dist2[j.first], j.first});
			}
		}
	}
	memset(dp, -1, sizeof(dp));
	ll mn = inf;
	for (int i = 1; i <= n; i++) mn = min(mn, ans(i, 0));
	ll mn2 = inf;
	memset(dp, -1, sizeof(dp));
	for (int i = 1; i <= n; i++) mn2 = min(mn2, ans2(i, 0));
	cout << min({dist[v], mn2, mn}) << '\n';
}

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