Submission #444687

#	Time	Username	Problem	Language	Result	Execution time	Memory
444687		aryan12	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	371 ms	23148 KiB

commuter_pass

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

mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());

const int N = 1e5 + 5, INF = 1e15;
vector<array<int, 2> > g[N];
vector<int> distS, distT, distU, distV;
vector<array<int, 2> > between;
int n, m;
int s, t, u, v;

bool cmp(array<int, 2> a, array<int, 2> b) {
	return a[0] < b[0];
}

void dijkstra(int src, vector<int> &dist) {
	dist[src] = 0;
	priority_queue<pair<int, int>, vector<pair<int, int> >, greater<pair<int, int> > > pq;
	pq.push(make_pair(dist[src], src));
	while(!pq.empty()) {
		int cur_dist = pq.top().first, node = pq.top().second;
		pq.pop();
		if(cur_dist != dist[node]) {
			continue;
		}
		for(int i = 0; i < g[node].size(); i++) {
			if(dist[g[node][i][0]] > dist[node] + g[node][i][1]) {
				dist[g[node][i][0]] = dist[node] + g[node][i][1];
				pq.push(make_pair(dist[g[node][i][0]], g[node][i][0]));
			}
		}
	}
}

void Solve() {
	cin >> n >> m >> s >> t >> u >> v;
	for(int i = 1; i <= m; i++) {
		int a, b, w;
		cin >> a >> b >> w;
		g[a].push_back({b, w});
		g[b].push_back({a, w});
	}
	distS.resize(n + 1);
	distT.resize(n + 1);
	distU.resize(n + 1);
	distV.resize(n + 1);
	for(int i = 0; i <= n; i++) {
		distS[i] = INF;
		distT[i] = INF;
		distU[i] = INF;
		distV[i] = INF;
	}
	dijkstra(s, distS);
	dijkstra(t, distT);
	dijkstra(u, distU);
	dijkstra(v, distV);

	/*cout << "distance from S\n";
	for(int i = 1; i <= n; i++) {
		cout << distS[i] << " ";
	}
	cout << "\n";

	cout << "distance from T\n";
	for(int i = 1; i <= n; i++) {
		cout << distT[i] << " ";
	}
	cout << "\n";

	cout << "distance from U\n";
	for(int i = 1; i <= n; i++) {
		cout << distU[i] << " ";
	}
	cout << "\n";

	cout << "distance from V\n";
	for(int i = 1; i <= n; i++) {
		cout << distV[i] << " ";
	}
	cout << "\n";*/

	for(int i = 1; i <= n; i++) {
		if(distS[i] + distT[i] == distS[t]) {
			between.push_back({distS[i], i});
		}
	}
	sort(between.begin(), between.end(), cmp);
	vector<array<int, 2> > dp(n + 1);
	for(int i = 0; i <= n; i++) {
		dp[i] = {INF, INF};
	}
	int curAns = distU[v];
	for(int i = 0; i < between.size(); i++) {
		int node = between[i][1];
		//cout << "node = " << node << "\n";
		dp[node][0] = min(dp[node][0], distU[node]);
		dp[node][1] = min(dp[node][1], distV[node]);
		for(int j = 0; j < g[node].size(); j++) {
			dp[g[node][j][0]][0] = min(dp[g[node][j][0]][0], dp[node][0]);
			dp[g[node][j][0]][1] = min(dp[g[node][j][0]][1], dp[node][1]);
		}
		curAns = min(curAns, dp[node][0] + distV[node]);
		curAns = min(curAns, dp[node][1] + distU[node]);
	}
	cout << curAns << "\n";
}

int32_t main() {
	auto begin = std::chrono::high_resolution_clock::now();
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int t = 1;
	//cin >> t;
	while(t--) {
		Solve();
	}
	auto end = std::chrono::high_resolution_clock::now();
    auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
    cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n"; 
	return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void dijkstra(long long int, std::vector<long long int>&)':
commuter_pass.cpp:28:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::array<long long int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |   for(int i = 0; i < g[node].size(); i++) {
      |                  ~~^~~~~~~~~~~~~~~~
commuter_pass.cpp: In function 'void Solve()':
commuter_pass.cpp:95:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::array<long long int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   95 |  for(int i = 0; i < between.size(); i++) {
      |                 ~~^~~~~~~~~~~~~~~~
commuter_pass.cpp:100:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::array<long long int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  100 |   for(int j = 0; j < g[node].size(); j++) {
      |                  ~~^~~~~~~~~~~~~~~~

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