test/DijkstraBuildPath.test.cpp

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Last update: 2021-03-22 17:28:05+09:00
Problem: https://judge.yosupo.jp/problem/shortest_path

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Code

#define PROBLEM "https://judge.yosupo.jp/problem/shortest_path"

#include "./../Graph/DijkstraBuildPath.cpp"
#include <iostream>
using namespace std;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int n, m, s, t;
	cin >> n >> m >> s >> t;

	Graph g(n);
	for (int i = 0; i < m; ++i) {
		int a, b;
		Weight c;
		cin >> a >> b >> c;
		g[a].emplace_back(b, c);
	}

	auto [dist, prev] = DijkstraBuildPrev(g, s);
	auto path = BuildPath(prev, t);

	if (dist[t] < INF) {
		cout << dist[t] << ' ' << path.size() - 1 << endl;
		for (size_t i = 0; i < path.size() - 1; i++) {
			cout << path[i] << ' ' << path[i + 1] << endl;
		}
	} else {
		cout << -1 << endl;
	}
}

#line 1 "test/DijkstraBuildPath.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/shortest_path"

#line 2 "Graph/GraphTemplate.cpp"
#include <vector>
#include <utility>
#include <iostream>
#include <limits>

using Weight = long long;
constexpr Weight INF = std::numeric_limits<Weight>::max();
struct Edge {
	int to;
	Weight cost;
	Edge() : to(-1), cost(-1) {}
	Edge(int _to, Weight _cost = 1) : to(_to), cost(_cost) {}
	friend bool operator<(const Edge& e1, const Edge& e2) {
		return e1.cost < e2.cost;
	}
	friend bool operator>(const Edge& e1, const Edge& e2) {
		return e1.cost > e2.cost;
	}
	friend std::ostream& operator<<(std::ostream& os, const Edge& e) {
		return os << "->" << e.to << '(' << e.cost << ')';
	}
};
using UnWeightedGraph = std::vector<std::vector<int>>;
using Graph = std::vector<std::vector<Edge>>;
struct Edge2 {
	int from, to;
	Weight cost;
	Edge2() : from(-1), to(-1), cost(0) {}
	Edge2(int _from, int _to, Weight _cost) : from(_from), to(_to), cost(_cost) {}
	friend bool operator<(const Edge2& e1, const Edge2& e2) {
		return e1.cost < e2.cost;
	}
	friend bool operator>(const Edge2& e1, const Edge2& e2) {
		return e1.cost > e2.cost;
	}
	friend std::ostream& operator<<(std::ostream& os, const Edge2& e) {
		return os << e.from << "->" << e.to << '(' << e.cost << ')';
	}
};
using UnWeightedEdges = std::vector<std::pair<int, int>>;
using Edges = std::vector<Edge2>;
using Matrix = std::vector<std::vector<Weight>>;

auto add_edge(UnWeightedGraph& graph, int v, int u) {
	graph[v].push_back(u);
	graph[u].push_back(v);
}
auto add_edge(Graph& graph, int v, int u, Weight cost) {
	graph[v].emplace_back(u, cost);
	graph[u].emplace_back(v, cost);
}
auto to_graph(const UnWeightedGraph& graph, Weight cost = 1) {
	Graph result(graph.size());
	for (std::size_t i = 0; i < graph.size(); ++i) {
		for (int v : graph[i]) {
			result[i].emplace_back(v, cost);
		}
	}
	return result;
}
auto to_unweighted_graph(const Graph& graph) {
	UnWeightedGraph result(graph.size());
	for (std::size_t i = 0; i < graph.size(); ++i) {
		for (auto [v, cost] : graph[i]) {
			result[i].push_back(v);
		}
	}
	return result;
}
auto to_edges(const UnWeightedGraph& graph, bool unique = false) {
	std::vector<std::pair<int, int>> edges;
	for (std::size_t i = 0; i < graph.size(); ++i) {
		for (int v : graph[i]) {
			if (!unique || static_cast<int>(i) < v) edges.emplace_back(i, v);
		}
	}
	return edges;
}
auto to_edges(const Graph& graph) {
	Edges edges;
	for (std::size_t i = 0; i < graph.size(); ++i) {
		for (auto [v, cost] : graph[i]) {
			edges.emplace_back(i, v, cost);
		}
	}
	return edges;
}
#line 4 "Graph/DijkstraBuildPath.cpp"
#include <queue>
#include <algorithm>
#include <functional>
#line 8 "Graph/DijkstraBuildPath.cpp"

auto DijkstraBuildPrev(const Graph& graph, int s) {
	std::size_t n = graph.size();
	std::vector<Weight> dist(n, INF);
	dist[s] = 0;
	std::vector<int> prev(n, -1);
	std::priority_queue<Edge, std::vector<Edge>, std::greater<Edge>> pq;
	pq.emplace(s, 0);
	while (!pq.empty()) {
		Edge p = pq.top();
		pq.pop();
		int v = p.to;
		if (dist[v] < p.cost) continue;
		for (auto e : graph[v]) {
			if (dist[e.to] > dist[v] + e.cost) {
				dist[e.to] = dist[v] + e.cost;
				pq.emplace(e.to, dist[e.to]);
				prev[e.to] = v;
			}
		}
	}
	return std::pair(dist, prev);
}
std::vector<int> BuildPath(const std::vector<int>& prev, int t) {
	std::vector<int> result;
	while (prev[t] != -1) {
		result.push_back(t);
		t = prev[t];
	}
	result.push_back(t);
	std::reverse(result.begin(), result.end());
	return result;
}
#line 5 "test/DijkstraBuildPath.test.cpp"
using namespace std;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int n, m, s, t;
	cin >> n >> m >> s >> t;

	Graph g(n);
	for (int i = 0; i < m; ++i) {
		int a, b;
		Weight c;
		cin >> a >> b >> c;
		g[a].emplace_back(b, c);
	}

	auto [dist, prev] = DijkstraBuildPrev(g, s);
	auto path = BuildPath(prev, t);

	if (dist[t] < INF) {
		cout << dist[t] << ' ' << path.size() - 1 << endl;
		for (size_t i = 0; i < path.size() - 1; i++) {
			cout << path[i] << ' ' << path[i + 1] << endl;
		}
	} else {
		cout << -1 << endl;
	}
}