Submission #771244

#	Time	Username	Problem	Language	Result	Execution time	Memory
771244		SamNguyen	Robot (JOI21_ho_t4)	C++14	100 / 100	145 ms	22500 KiB

Main

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

template <class T> 
using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;

const lli INF = 0x1f1f1f1f1f1f1f1f;
const int MAX_N = 1e5 + 7;
const int MAX_M = 2e5 + 7;

template <class T1, class T2>
inline constexpr bool minimise(T1 &x, T2 y) {
	if (x > y) { x = y; return true; }
	return false;
}

template <class T1, class T2>
inline constexpr bool maximise(T1 &x, T2 y) {
	if (x < y) { x = y; return true; }
	return false;
}

class Edge {
private:
	int u, v, c;
	lli w;

public:
	Edge(int u = 0, int v = 0, int c = 0, lli w = 0): u(u), v(v), c(c), w(w) {}

	inline lli cost() const { return w; }
	inline pair<int, int> nodes() const { return make_pair(u, v); }
	inline int other_node(int z) const { return u ^ v ^ z; }
	inline int colour() const { return c; }

	inline int get_node(bool is_rev) const { return is_rev ? v : u; }
	inline bool is_start(int z) const { return z == u; }
};

int N, M;
Edge edge[MAX_M];
vector<int> adj[MAX_N];

void input() {
	cin >> N >> M;
	for (int i = 0; i < M; i++) {
		int u, v, c; lli w;
		cin >> u >> v >> c >> w;
		edge[i] = Edge(u, v, c, w);
		adj[u].push_back(i);
		adj[v].push_back(i);
	}
}

lli dist[MAX_N];
min_priority_queue<pair<lli, int>> pq;
lli sum_by_colour[MAX_M], min_by_colour[MAX_M];

lli solve() {
	memset(dist, 0x1f, sizeof dist);
	memset(sum_by_colour, 0, sizeof sum_by_colour);
	memset(min_by_colour, 0x1f, sizeof min_by_colour);

	auto relax = [&](int u, lli d) {
		if (minimise(dist[u], d))
			pq.emplace(d, u);
	};

	relax(1, 0);

	lli ans = INF;
	while (not pq.empty()) {
		lli cur_dist; int u;
		tie(cur_dist, u) = pq.top();
		pq.pop();

		if (u == N) 
			minimise(ans, cur_dist);

		if (cur_dist > dist[u])
			continue;

		for (int j : adj[u]) {
			int v = edge[j].other_node(u);
			int c = edge[j].colour();
			lli w = edge[j].cost();

			sum_by_colour[c] += w;
			minimise(min_by_colour[c], dist[v]);
		}

		for (int j : adj[u]) {
			int v = edge[j].other_node(u);
			int c = edge[j].colour();
			lli w = edge[j].cost();

			relax(v, cur_dist + min(w, sum_by_colour[c] - w));
			relax(v, min_by_colour[c] + sum_by_colour[c] - w);
		}

		for (int j : adj[u]) {
			int c = edge[j].colour();
			sum_by_colour[c] = 0;
			min_by_colour[c] = INF;
		}
	}

	if (ans >= INF)
		ans = -1;
	return ans;
}

int main(void) {
	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);

	input();
	cout << solve();

	return 0;
}

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