feat: Add C++ code for the graph bfs and dfs (#401)

* Add C++ code for the graph bfs and dfs

* Add C++ code for the graph bfs and dfs

codes/cpp/chapter_graph/graph_adjacency_list.cpp

@@ -1,24 +1,27 @@
 /**
  * File: graph_adjacency_list.cpp
  * Created Time: 2023-02-09
- * Author: what-is-me (whatisme@outlook.jp)
+ * Author: what-is-me (whatisme@outlook.jp), Krahets (krahets@163.com)
  */
 
 #include "../include/include.hpp"
 
-/* 顶点类 */
-struct Vertex {
-    int val;
-    Vertex(int val) : val(val) {}
-};
-
 /* 基于邻接表实现的无向图类 */
 class GraphAdjList {
-    // 邻接表，使用哈希表来代替链表，以提升删除边、删除顶点的效率
-    // 请注意，adjList 中的元素是 Vertex 对象
-    unordered_map<Vertex*, unordered_set<Vertex*>> adjList;
-
 public:
+    // 邻接表，key: 顶点，value：该顶点的所有邻接顶点
+    unordered_map<Vertex*, vector<Vertex*>> adjList;
+    
+    /* 在 vector 中删除指定结点 */
+    void remove(vector<Vertex*> &vec, Vertex *vet) {
+        for (int i = 0; i < vec.size(); i++) {
+            if (vec[i] == vet) {
+                vec.erase(vec.begin() + i);
+                break;
+            }
+        }
+    }
+
     /* 构造方法 */
     GraphAdjList(const vector<vector<Vertex*>>& edges) {
         // 添加所有顶点和边
@@ -37,8 +40,8 @@ public:
         if (!adjList.count(vet1) || !adjList.count(vet2) || vet1 == vet2)
             throw invalid_argument("不存在顶点");
         // 添加边 vet1 - vet2
-        adjList[vet1].insert(vet2);
-        adjList[vet2].insert(vet1);
+        adjList[vet1].push_back(vet2);
+        adjList[vet2].push_back(vet1);
     }
 
     /* 删除边 */
@@ -46,15 +49,15 @@ public:
         if (!adjList.count(vet1) || !adjList.count(vet2) || vet1 == vet2)
             throw invalid_argument("不存在顶点");
         // 删除边 vet1 - vet2
-        adjList[vet1].erase(vet2);
-        adjList[vet2].erase(vet1);
+        remove(adjList[vet1], vet2);
+        remove(adjList[vet2], vet1);
     }
 
     /* 添加顶点 */
     void addVertex(Vertex* vet) {
         if (adjList.count(vet)) return;
         // 在邻接表中添加一个新链表
-        adjList[vet] = unordered_set<Vertex*>();
+        adjList[vet] = vector<Vertex*>();
     }
 
     /* 删除顶点 */
@@ -64,67 +67,19 @@ public:
         // 在邻接表中删除顶点 vet 对应的链表
         adjList.erase(vet);
         // 遍历其它顶点的链表，删除所有包含 vet 的边
-        for (auto& [key, set_] : adjList) {
-            set_.erase(vet);
+        for (auto& [key, vec] : adjList) {
+            remove(vec, vet);
         }
     }
 
     /* 打印邻接表 */
     void print() {
         cout << "邻接表 =" << endl;
-        for (auto& [key, value] : adjList) {
-            vector<int> tmp;
-            for (Vertex* vertex : value)
-                tmp.push_back(vertex->val);
+        for (auto& [key, vec] : adjList) {
             cout << key->val << ": ";
-            PrintUtil::printVector(tmp);
+            PrintUtil::printVector(vetsToVals(vec));
         }
     }
 };
 
-
-/* Driver Code */
-int main() {
-    /* 初始化无向图 */
-    Vertex *v0 = new Vertex(1),
-           *v1 = new Vertex(3),
-           *v2 = new Vertex(2),
-           *v3 = new Vertex(5),
-           *v4 = new Vertex(4);
-    vector<vector<Vertex*>> edges = {{v0, v1}, {v1, v2}, {v2, v3}, {v0, v3}, {v2, v4}, {v3, v4}};
-    GraphAdjList graph(edges);
-    cout << "\n初始化后，图为" << endl;
-    graph.print();
-
-    /* 添加边 */
-    // 顶点 1, 2 即 v0, v2
-    graph.addEdge(v0, v2);
-    cout << "\n添加边 1-2 后，图为" << endl;
-    graph.print();
-
-    /* 删除边 */
-    // 顶点 1, 3 即 v0, v1
-    graph.removeEdge(v0, v1);
-    cout << "\n删除边 1-3 后，图为" << endl;
-    graph.print();
-
-    /* 添加顶点 */
-    Vertex* v5 = new Vertex(6);
-    graph.addVertex(v5);
-    cout << "\n添加顶点 6 后，图为" << endl;
-    graph.print();
-
-    /* 删除顶点 */
-    // 顶点 3 即 v1
-    graph.removeVertex(v1);
-    cout << "\n删除顶点 3 后，图为" << endl;
-    graph.print();
-
-    /* 释放内存 */
-    delete v0;
-    delete v1;
-    delete v2;
-    delete v3;
-    delete v4;
-    delete v5;
-}
+// GraphAdjList 的测试样例在 graph_adjacency_list_test.cpp 文件中