Submission #925318

#	Time	Username	Problem	Language	Result	Execution time	Memory
925318		crafticat	Robot (JOI21_ho_t4)	C++17	100 / 100	872 ms	84632 KiB

Main

#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;
}

• Subtask 1: 34 / 34
• Subtask 2: 24 / 24
• Subtask 3: 42 / 42