Submission #368213

#TimeUsernameProblemLanguageResultExecution timeMemory
368213ijxjdjdCommuter Pass (JOI18_commuter_pass)C++17
100 / 100
449 ms23656 KiB
#include <bits/stdc++.h>
#define FR(i, N) for (int i = 0; i < int(N); i++)
#define all(x) begin(x), end(x)
#define f first
#define s second
using namespace std;

using ll = long long;

const int MAXN = 100000;
vector<pair<int, int>> adj[MAXN];
const ll INF = (ll)(1e18);
int N, M;
int pass[2];
ll dist[4][MAXN];
ll distPass[2][MAXN];
int start, stop;
void dijkstraPass(int s) {
    priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<pair<ll, int>>> pq;
    FR(i, MAXN) {
        distPass[s][i] = INF;
    }
    distPass[s][pass[s]] = 0;
    pq.push({0, pass[s]});
    while (pq.size()) {
        auto [d, n] = pq.top();
        pq.pop();
        if (distPass[s][n] == d) {
            for (auto [e, w] : adj[n]) {
                if (distPass[s][e] > distPass[s][n] + w) {
                    distPass[s][e] = distPass[s][n] + w;
                    pq.push({distPass[s][e], e});
                }
            }
        }
    }
}
int main() {
	cin.tie(0);
	cin.sync_with_stdio(0);
	cin >> N >> M;
	cin >> pass[0] >> pass[1];
	cin >> start >> stop;
	pass[0]--, pass[1]--, start--, stop--;
	FR(i, M) {
        int u, v, w;
        cin >> u >> v >> w;
        u--, v--;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
	}
	dijkstraPass(0);
	dijkstraPass(1);
    priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<pair<ll, int>>> pq;
    FR(i, 4) FR(j, MAXN) dist[i][j] = INF;
    dist[0][start] = 0;
    pq.push({0, start});
    ll minDist = distPass[0][pass[1]];
    while (pq.size()) {
        auto[d, n] = pq.top();
        pq.pop();
        int state = n/N;
        n%=N;
        if (dist[state][n] == d) {
            if (state == 0 || state == 3) {
                for (auto [e, w] : adj[n]) {
                    if (dist[state][e] > dist[state][n] + w) {
                        dist[state][e] = dist[state][n] + w;
                        pq.push({dist[state][e], state*N + e});
                    }
                }
            }
            if (state == 0) {
                for (auto [e, w] : adj[n]) {
                    if (distPass[0][n] + distPass[1][e] + w == minDist && dist[2][e] > d) {
                        dist[2][e] = d;
                        pq.push({d, 2*N + e});
                    }
                    if (distPass[1][n] + distPass[0][e] + w == minDist && dist[1][e] > d) {
                        dist[1][e] = d;
                        pq.push({d, N + e});
                    }
                }
            }
            if (state == 1 || state == 2) {
                for (auto [e, w] : adj[n]) {
                    if ((state == 1 ? distPass[1][n] + distPass[0][e] + w : distPass[0][n] + distPass[1][e] + w) == minDist && dist[state][e] > d) {
                        dist[state][e] = d;
                        pq.push({d, state*N + e});
                    }
                }
            }
            if (dist[3][n] > d) {
                pq.push({d, 3*N + n});
                dist[3][n] = d;
            }
        }
    }
    cout << dist[3][stop] << '\n';
	return 0;
}
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