Language: C++

#include <iostream>
#include <vector>
#include <queue>
#include <functional>
#include <string>

class Graph {
public:
	// エッジ
	struct Edge {
		// 接続先のノード番号
		int node;
		// 移動コスト
		int cost;
		// コンストラクタ
		Edge(const int node, const int cost) : node(node), cost(cost) {	}
	};
	// ノード
	struct Node {
		// エッジ
		std::vector<Edge> edges_;
	};

	// コンストラクタ
	Graph(std::istream& in) {
		// 総ノード数の読み込み
		int n;
		in >> n;
		// ノード用配列を初期化
		nodes_.resize(n);

		// 総エッジ数の抽出
		int e;
		in >> e;

		// 開始ノードの抽出
		int start;
		in >> start;
		start_ = start;

		// 1
		// エッジデータの読み込み
		for (int i = 0; i != e; ++i) {
			// 始点・終点のノードの番号を読み込む
			int s, t, c;
			// s 始点ノード, t 近隣ノード, c コスト
			in >> s >> t >> c;
			// ノードに近隣ノードの番号を登録
			nodes_[s].edges_.emplace_back(t, c);
		}
	}

	// ノードを取得
	const Node& operator[](int index) const { return nodes_[index]; }
	// ノード数を取得
	std::size_t node_count() const { return nodes_.size(); }
	// 開始ノードの取得
	int start_node() const { return start_; }

private:
	// ノード用配列
	std::vector<Node> nodes_;
	// 開始ノード
	int start_;
};

class PathFinder {
	// 距離とノード番号のペア
	using dist_node = std::pair<float, int>;

public:
	// パス検索
	static std::vector<std::string> find_path(const Graph& graph) {
		// 初期値を最大値にする
		// 最大値の取得
		const auto inf = std::numeric_limits<float>::max();
		// 経路情報
		// 始めに個数と番号を指定して作成する
		// { 合計コスト, 親の番号 }
		std::vector<dist_node> dist_nodes(graph.node_count(), { inf, -1 });
		// プライオリティキュー
		// 合計コストが少ないパスを取得する greater<>
		std::priority_queue<dist_node, std::vector<dist_node>, std::greater<dist_node>> queue;
		// 開始ノードをキューに登録
		dist_nodes[graph.start_node()] = { 0.0f, -1 };
		queue.push({ 0.0f, graph.start_node() });
		// キューにデータがあるか？
		while (!queue.empty()) {
			// 先頭ノードをキューから取り出す
			const auto front = queue.top();
			// pop でデータを捨てる
			queue.pop();
			const auto front_g = front.first;
			const auto front_node = front.second;
			const int end = 3;
			// ゴールにたどりついたか
			if (front_node == end) {
				// ここの返す配列を各パスの総コストとする
				return create_cost(dist_nodes);
				//return create_path(dist_nodes, end);
			}

			// キュー内のデータよりも経路情報の合計距離が小さいか？
			// キュー内のデータは最短距離ではないので無視
			// 情報を毎回更新する
			if (dist_nodes[front_node].first < front_g) continue;
			// 近隣ノードを取得
			// for (const auto& node : graph[front_node].nodes_) 
			for (const auto& edge : graph[front_node].edges_) {
				const auto g = dist_nodes[front_node].first + edge.cost;
				// 親ノードまでのコストの合計値と比較して、値が小さければ更新する
				if (dist_nodes[edge.node].first > g) {
					// 経路情報を保存
					dist_nodes[edge.node] = { g, front_node };
					// キューに登録
					queue.push({ g, edge.node });
				}
				//// 合計距離を求める(移動コストは1.0とする)
				//const auto g = dist_nodes[front_node].first + 1.0f;
				//// 合計距離が小さい場合は最短経路としてキューに登録
				//if (dist_nodes[node].first > g) {
				//	// 経路情報を保存
				//	dist_nodes[node] = { g, front_node };
				//	// キューに登録
				//	queue.push({ g, node });
				//}
			}
		}
		// 経路が見つからない場合でも検索していたパスを返す
		return create_cost(dist_nodes);
	}

private:
	// パスの作成
	static std::vector<std::string> create_path(const std::vector<dist_node>& dist_nodes, int end) {
		std::vector<std::string> path;
		for (int node = end; node != -1; node = dist_nodes[node].second) {
			path.push_back(std::to_string(node));
		}

		return path;
	}

	// コスト一覧の生成
	static std::vector<std::string> create_cost(const std::vector<dist_node>& dist_nodes) {
		std::vector<std::string> path;
		for (int i = 0; i != dist_nodes.size(); ++i) {
			std::string cost = std::to_string((int)dist_nodes[i].first);
			auto inf = std::numeric_limits<float>::max();
			// 無限値の場合は、INFを表示する
			if (dist_nodes[i].first == inf) cost = "INF";
			path.push_back(cost);
		}

		return path;
	}
};

int main() {
	Graph graph(std::cin);
	auto path = PathFinder::find_path(graph);
	// 経路パスの表示(逆順)
	for (auto node_id : path) {
		std::cout << node_id << std::endl;
	}

	return 0;
}


Compiler output:
a.cc: In static member function 'static std::vector<std::__cxx11::basic_string<char> > PathFinder::find_path(const Graph&)':
a.cc:76:39: error: 'numeric_limits' is not a member of 'std'
   76 |                 const auto inf = std::numeric_limits<float>::max();
      |                                       ^~~~~~~~~~~~~~
a.cc:76:54: error: expected primary-expression before 'float'
   76 |                 const auto inf = std::numeric_limits<float>::max();
      |                                                      ^~~~~
a.cc:80:82: error: no matching function for call to 'std::vector<std::pair<float, int> >::vector(std::size_t, <brace-enclosed initializer list>)'
   80 |                 std::vector<dist_node> dist_nodes(graph.node_count(), { inf, -1 });
      |                                                                                  ^
In file included from /usr/include/c++/14/vector:66,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_vector.h:707:9: note: candidate: 'template<class _InputIterator, class> std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const allocator_type&) [with <template-parameter-2-2> = _InputIterator; _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >]'
  707 |         vector(_InputIterator __first, _InputIterator __last,
      |         ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:707:9: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/14/bits/stl_iterator_base_funcs.h:66,
                 from /usr/include/c++/14/string:47,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_iterator_base_types.h: In substitution of 'template<class _InIter> using std::_RequireInputIter = std::__enable_if_t<((bool)std::is_convertible<typename std::iterator_traits< <template-parameter-1-1> >::iterator_category, std::input_iterator_tag>::value)> [with _InIter = long unsigned int]':
/usr/include/c++/14/bits/stl_vector.h:705:9:   required from here
  705 |                typename = std::_RequireInputIter<_InputIterator>>
      |                ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator_base_types.h:252:57: error: no type named 'iterator_category' in 'struct std::iterator_traits<long unsigned int>'
  252 |                                    input_iterator_tag>::value>;
      |                                                         ^~~~~
/usr/include/c++/14/bits/stl_vector.h:678:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::initializer_list<_Tp>, const allocator_type&) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >; allocator_type = std::allocator<std::pair<float, int> >]'
  678 |       vector(initializer_list<value_type> __l,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:678:43: note:   no known conversion for argument 1 from 'std::size_t' {aka 'long unsigned int'} to 'std::initializer_list<std::pair<float, int> >'
  678 |       vector(initializer_list<value_type> __l,
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:659:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, std::__type_identity_t<_Alloc>&) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >; std::__type_identity_t<_Alloc> = std::allocator<std::pair<float, int> >]'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:659:23: note:   no known conversion for argument 1 from 'std::size_t' {aka 'long unsigned int'} to 'std::vector<std::pair<float, int> >&&'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |              ~~~~~~~~~^~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::false_type) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >; allocator_type = std::allocator<std::pair<float, int> >; std::false_type = std::false_type]'
  640 |       vector(vector&& __rv, const allocator_type& __m, false_type)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:635:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::true_type) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >; allocator_type = std::allocator<std::pair<float, int> >; std::true_type = std::true_type]'
  635 |       vector(vector&& __rv, const allocator_type& __m, true_type) noexcept
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:635:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:624:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&, std::__type_identity_t<_Alloc>&) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >; std::__type_identity_t<_Alloc> = std::allocator<std::pair<float, int> >]'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:624:28: note:   no known conversion for argument 1 from 'std::size_t' {aka 'long unsigned int'} to 'const std::vector<std::pair<float, int> >&'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |              ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >]'
  620 |       vector(vector&&) noexcept = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:601:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >]'
  601 |       vector(const vector& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:601:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:569:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const value_type&, const allocator_type&) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >; size_type = long unsigned int; value_type = std::pair<float, int>; allocator_type = std::allocator<std::pair<float, int> >]'
  569 |       vector(size_type __n, const value_type& __value,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:569:47: note:   no known conversion for argument 2 from '<brace-enclosed initializer list>' to 'const std::vector<std::pair<float, int> >::value_type&' {aka 'const std::pair<float, int>&'}
  569 |       vector(size_type __n, const value_type& __value,
      |                             ~~~~~~~~~~~~~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const allocator_type&) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >; size_type = long unsigned int; allocator_type = std::allocator<std::pair<float, int> >]'
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:51: note:   no known conversion for argument 2 from '<brace-enclosed initializer list>' to 'const std::vector<std::pair<float, int> >::allocator_type&' {aka 'const std::allocator<std::pair<float, int> >&'}
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |                             ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const allocator_type&) [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >; allocator_type = std::allocator<std::pair<float, int> >]'
  542 |       vector(const allocator_type& __a) _GLIBCXX_NOEXCEPT
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:531:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector() [with _Tp = std::pair<float, int>; _Alloc = std::allocator<std::pair<float, int> >]'
  531 |       vector() = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:531:7: note:   candidate expects 0 arguments, 2 provided
a.cc: In static member function 'static std::vector<std::__cxx11::basic_string<char> > PathFinder::create_cost(const std::vector<std::pair<float, int> >&)':
a.cc:149:41: error: 'numeric_limits' is not a member of 'std'
  149 |                         auto inf = std::numeric_limits<float>::max();
      |                                         ^~~~~~~~~~~~~~
a.cc:149:56: error: expected primary-expression before 'float'
  149 |                         auto inf = std::numeric_limits<float>::max();
      |                                                        ^~~~~