2021.6.7 Undirected-graph

unigraph.cpp

+
+#include <iostream>
+#include <utility>
+
+/// <summary>
+/// 教材 p.362
+/// 具有固定结点数的无向图的邻接多重表实现  或十字链表
+/// 仍然采用int在内部表示结点
+/// </summary>
+template <typename V, typename E>
+class UniGraph {
+public:
+	//表示从v1到v2的有向边
+	struct Edge {
+		E edata;
+		int v1, v2;
+		Edge* path1;   //出边表
+		Edge* path2;   //入边表
+		Edge() :edata(), v1(), v2(), path1(nullptr), path2(nullptr) {}
+		Edge(int v1_, int v2_, const E& data) :edata(data), v1(v1_), v2(v2_),
+			path1(nullptr), path2(nullptr) {}
+	};
+	struct Vertex {
+		V vdata;
+		Edge* outed;   //出边表
+		Vertex() :vdata(), outed(nullptr) {}
+	};
+
+	UniGraph(int size_);
+	~UniGraph()noexcept;
+
+	Edge* add_edge(int from, int to, const E& data);
+	void remove_edge(int from, int to);  //需要时实现
+
+	inline Edge* first_edge(int v) {
+		return vertices[v].outed;
+	}
+	Edge* next_edge(int v, Edge* e);
+
+	inline int get_edge_neighbour(int u, const Edge* e)const {
+		return u == e->v1 ? e->v2 : e->v1;
+	}
+
+	inline int get_size()const {
+		return size;
+	}
+
+	Edge* get_edge(int u, int v);
+
+	UniGraph(const UniGraph&) = delete;
+	UniGraph(UniGraph&&) = delete;
+	UniGraph& operator=(const UniGraph&) = delete;
+	UniGraph& operator=(UniGraph&&) = delete;
+
+protected:
+	int size;    //顶点数
+	Vertex* vertices;
+
+	//path1或者path2指针域
+	Edge*& next_edge_ref(int v, Edge* e);
+
+	//来向的指针
+	Edge* previous_edge(int v, Edge* e);
+};
+
+template<typename V, typename E>
+UniGraph<V, E>::UniGraph(int size_) :size(size_)
+{
+	vertices = new Vertex[size];
+}
+
+template<typename V, typename E>
+UniGraph<V, E>::~UniGraph() noexcept
+{
+	//先按照出边顺序清除表
+	for (int i = 0; i < size; i++) {
+		auto e = vertices[i].outed;
+		if (e) {
+			auto e1 = next_edge(i, e);
+			while (e1) {
+				if (e->v2 >= 0) {
+					//用v2为-1作为已经访问过一次的判据
+					//注意这个强烈依赖于判定next_edge时仅用了v1!!
+					e->v2 = -1;
+				}
+				else {
+					delete e;
+				}
+
+				e = e1;
+				e1 = next_edge(i, e1);
+			}
+		}
+	}
+	delete[] vertices;
+	vertices = nullptr;
+}
+
+//注意 插入到各个边的链表的第一位
+template<typename V, typename E>
+typename UniGraph<V, E>::Edge*
+UniGraph<V, E>::add_edge(int from, int to, const E& data)
+{
+	auto e = new Edge(from, to, data);
+	e->path1 = vertices[from].outed;
+	vertices[from].outed = e;
+	e->path2 = vertices[to].outed;
+	vertices[to].outed = e;
+	return e;
+}
+
+template<typename V, typename E>
+typename UniGraph<V,E>::Edge* UniGraph<V, E>::next_edge(int v, Edge* e)
+{
+	if (v == e->v1) {
+		return e->path1;
+	}
+	else return e->path2;
+}
+
+template<typename V, typename E>
+typename UniGraph<V, E>::Edge*& UniGraph<V, E>::next_edge_ref(int v, Edge* e)
+{
+	if (v == e->v1) {
+		return e->path1;
+	}
+	else return e->path2;
+}
+
+template<typename V, typename E>
+typename UniGraph<V,E>::Edge* UniGraph<V, E>::previous_edge(int v, Edge* e)
+{
+	if (v == e->v1) {
+		return e->path2;
+	}
+	else return e->path1;
+}
+
+template<typename V, typename E>
+typename UniGraph<V, E>::Edge* UniGraph<V, E>::get_edge(int u, int v)
+{
+	auto* e = first_edge(u);
+	for (; e; e = next_edge(u,e)) {
+		if ((e->v1 == v && e->v2 == u) || (e->v2 == v && e->v1 == u)) {
+			return e;
+		}
+	}
+	return nullptr;
+}
+