Submission #1185902

#TimeUsernameProblemLanguageResultExecution timeMemory
1185902vincentbucourt1Robot (JOI21_ho_t4)C++20
100 / 100
619 ms79204 KiB
#include <bits/stdc++.h>

typedef long long ll;

using namespace std;


const ll INF = 1e18;


struct Edge {

	int to, c;

	ll p;

};


map<int, vector<Edge>> graph[100001];

ll dp[100001];

map<int, ll> dp2[100001], psum[100001];


int main() {

	cin.tie(0)->sync_with_stdio(0);

	int n, m;

	cin >> n >> m;

	for (int i = 1; i <= m; i++) {

		int u, v, c;

		ll p;

		cin >> u >> v >> c >> p;

		graph[u][c].push_back({v, c, p});

		graph[v][c].push_back({u, c, p});

		psum[u][c] += p;

		psum[v][c] += p;

	}


	memset(dp, 0x3f, sizeof dp);

	dp[1] = 0;

	priority_queue<tuple<ll, int, int>> pq;

	pq.push({0, 1, 0});

	while (pq.size()) {

		ll cost;

		int node, c;

		tie(cost, node, c) = pq.top();

		pq.pop();


		if (c) {

			if (dp2[node][c] != -cost) continue;

			for (Edge i : graph[node][c]) {

				// We can't flip i in this case

				ll case1 = psum[node][c] - i.p;

				if (case1 - cost < dp[i.to]) {

					dp[i.to] = case1 - cost;

					pq.push({-dp[i.to], i.to, 0});

				}

			}

		} else {

			if (dp[node] != -cost) continue;

			for (auto &i : graph[node]) {

				for (Edge j : i.second) {

					// Case 1: We don't flip j

					ll case1 = psum[node][j.c] - j.p - cost;

					if (case1 < dp[j.to]) {

						dp[j.to] = case1;

						pq.push({-dp[j.to], j.to, 0});

					}

					// Case 2: We flip j but not another edge of the same colour

					ll case2 = j.p - cost;

					if (case2 < dp[j.to]) {

						dp[j.to] = case2;

						pq.push({-dp[j.to], j.to, 0});

					}

					// Case 3: We flip j and another edge of the same colour

					ll case3 = -cost;

					if (!dp2[j.to].count(j.c) || case3 < dp2[j.to][j.c]) {

						dp2[j.to][j.c] = case3;

						pq.push({-dp2[j.to][j.c], j.to, j.c});

					}

				}

			}

		}

	}

	cout << (dp[n] > INF ? -1 : dp[n]);

	return 0;

}
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