Submission #874317

#	Time	Username	Problem	Language	Result	Execution time	Memory
874317		tsumondai	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	364 ms	91568 KiB

commuter_pass

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

#define int long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, r, l) for(int i = r; i >= l; i--)
#define __TIME  (1.0 * clock() / CLOCKS_PER_SEC)

typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;

const int N = 1e6 + 5;

const int oo = 1e18, mod = 1e9 + 7;

int n, m, k, points[5], vis[N], dpU[N], dpV[N], ans;

vector<ii> adj[N];
vector<int> dag[N];

int dist[N][5];

bool mini(int &a, const int b) {
	if (a > b) {
		a = b; return true;
	} else {
		return false;
	}
}

bool maxi(int &a, const int b) {
	if (a < b) {
		a = b;
		return true;
	} else {
		return false;
	}
}

void dfs(int x, int p) {
    if (vis[x]) return;
    vis[x] = 1;
    for (int y : dag[x]) {
        if (y != p) {
            dfs(y, x);
            dpU[x] = min({dpU[x], dpU[y], dist[y][3]});
            dpV[x] = min({dpV[x], dpV[y], dist[y][4]});
        }
    }
    ans = min(ans, dpU[x] + dist[x][4]);
    ans = min(ans, dpV[x] + dist[x][3]);
}

void dijkstra(int s) {
	foru(i, 1, n) dist[i][s] = oo;
	priority_queue <pair <long long, int>> pq;
	pq.push(make_pair(dist[points[s]][s] = 0, points[s]));
	while (!pq.empty()) {
		//auto [du, u] = pq.top(); pq.pop();
		pair<long long, long long> tmp = pq.top(); pq.pop();
		long long du = tmp.first, u = tmp.second;

		du = -du;
		if (du != dist[u][s]) continue;
		/* for (auto [w, v]: adj[u]) if (dist[v] > du + w) {
		     dist[v] = du + w;
		     pq.push(make_pair(-dist[v], v));
		 }*/
		for (pair<long long, long long> nxt : adj[u]) if (dist[nxt.second][s] > du + nxt.first) {
				dist[nxt.second][s] = du + nxt.first;
				pq.push(make_pair(-dist[nxt.second][s], nxt.second));
			}
	}
}

void process() {
	cin >> n >> m;// 1 2 3 4
	foru(i, 1, 4) cin >> points[i];
	foru(i, 1, m) {
		int u, v, c;
		cin >> u >> v >> c;
		adj[u].pb({c, v});
		adj[v].pb({c, u});
	}

	foru(i, 1, 4) dijkstra(i);

	foru(x, 1, n) {
		for (auto tmp : adj[x]) {
			int y = tmp.se, w = tmp.fi;
			if (dist[x][1] + w + dist[y][2] == dist[points[2]][1]) {
				dag[x].pb(y);
			}
		}
	}

	ans = dist[points[3]][4];
	memset(dpU, 0x3f, sizeof(dpU));
	memset(dpV, 0x3f, sizeof(dpV));
	dfs(points[1], 0);
	cout << ans;
	return;
}

signed main() {
	cin.tie(0)->sync_with_stdio(false);
	//freopen(".inp", "r", stdin);
	//freopen(".out", "w", stdout);
	process();
	cerr << "Time elapsed: " << __TIME << " s.\n";
	return 0;
}

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