Adjacency List表示下Depth-First-Search(DFS)及Breadth-First-Search(BFS)的c++实现

1. Interface (Graph.h, listQueue.h)

#ifndef GRAPH_H_INCLUDED#define GRAPH_H_INCLUDEDclass Graph{private:struct adjListNode{int node;adjListNode* next;adjListNode(int x, adjListNode* t) : node(x), next(t) {}};typedef adjListNode* vtx;vtx* adjList;// adjacency listint countV;// number of vertices in the graphvoid dfsUtil(int, bool*);// recursive procedure in DFSpublic:Graph(int);~Graph();void addEdge(int, int);void removeEdge(int, int);bool isConnected(int, int);void showConnected(int);void dfs(int);void bfs(int);};#endif // GRAPH_H_INCLUDED

#ifndef LISTQUEUE_H_INCLUDED#define LISTQUEUE_H_INCLUDEDtemplate <class Item>class Queue{private:struct node{Item item;node *next;node(Item x) : item(x), next(0) {}};typedef node *link;link head, tail;// enqueue to the tail, dequeue from the headpublic:Queue();~Queue();bool isEmpty() const;void enqueue(Item);// push item into the queueItem dequeue();// retrieve item back from the queue};template <class Item>Queue<Item>::Queue(){head = 0;tail = 0;}template <class Item>Queue<Item>::~Queue(){delete head;}template <class Item>bool Queue<Item>::isEmpty() const{return head == 0;}template <class Item>void Queue<Item>::enqueue(Item x){link t = tail;tail = new node(x);if (head == 0)head = tail;else t->next = tail;}template <class Item>Item Queue<Item>::dequeue(){Item v = head->item;link t = head->next;delete head;head = t;return v;}#endif // LISTQUEUE_H_INCLUDED

2. Implementation (Graph.cpp)

/* Represent graphs by adjacency list without dummy head node. */#include"Graph.h"#include"listQueue.h"#include<iostream>using namespace std;Graph::Graph(int N){countV = N;adjList = new vtx[countV];for (int i = 0; i < N; ++i){adjList[i] = new adjListNode(i, 0);}}Graph::~Graph(){for (int i = 0; i < countV; ++i)delete[] adjList[i];delete[] adjList;}void Graph::addEdge(int x, int y){if (x >= 0 && x < countV && y >= 0 && y < countV){adjList[x] = new adjListNode(y, adjList[x]);}}bool Graph::isConnected(int x, int y){int check = 0;if (x >= 0 && x < countV && y >= 0 && y < countV){vtx newNode = adjList[x];while (newNode->next != 0){if (newNode->node == y){check = 1;break;}else newNode = newNode->next;}}return check;}void Graph::removeEdge(int x, int y){if (x >= 0 && x < countV && y >= 0 && y < countV){vtx newNode1 = adjList[x], newNode2 = adjList[x];int countLoop = 0;while (newNode1->node != y && newNode1->next != 0){newNode2 = newNode1;newNode1 = newNode2->next;++countLoop;}if (!countLoop){newNode2 = newNode1->next;adjList[x] = newNode2;}else{newNode2->next = newNode1->next;adjList[x] = newNode2;}}}void Graph::showConnected(int x){cout << "The connection of vertex " << x << ":" << endl;vtx newNode = adjList[x];while (newNode->next != 0){cout << newNode->node << " -> ";newNode = newNode->next;}cout << x << endl;}void Graph::dfsUtil(int v, bool* visited){visited[v] = true;vtx newNode1 = adjList[v];while (newNode1->next != 0){if (!visited[newNode1->node]){// output the node (v, newNode1->node)cout << "(" << v << ", " << newNode1->node << ")" << endl;// recursiondfsUtil(newNode1->node, visited);}else{newNode1 = newNode1->next;}}}void Graph::dfs(int v){bool* visited = new bool[countV];for (int i = 0; i < countV; ++i)visited[i] = false;dfsUtil(v, visited);}void Graph::bfs(int v){Queue<int> q;bool* visited = new bool[countV];for (int i = 0; i < countV; ++i)visited[i] = false;q.enqueue(v);visited[v] = true;while (!q.isEmpty()){int temp = q.dequeue();while (adjList[temp]->next != 0){if (!visited[adjList[temp]->node]){q.enqueue(adjList[temp]->node);visited[adjList[temp]->node] = true;cout << "(" << temp << ", " << adjList[temp]->node << ")" << endl;}adjList[temp] = adjList[temp]->next;}}delete[] visited;}

3. Client (main.cpp)

#include<iostream>#include"Graph.h"using namespace std;int main(int argc, char* argv[]){int V = atoi(argv[1]);Graph *g = new Graph(V);for (int i = 0; i < V; ++i){cout << "Enter the connections of vertex " << i << ":" << endl;int j;while (cin >> j){if (j >= 0 && j < V && j != i){g->addEdge(i, j);}else if (j == i){

// if the input vertex is the same as the given vertexbreak;}else cout << "Out of range." << endl;}}for (int i = 0; i < V; ++i)g->showConnected(i);// DFSint start = 0;cout << "Enter the DFS starting node:";cin >> start;g->dfs(start);// BFScout << "Enter the BFS starting node:";cin >> start;g->bfs(start);return 0;}

测试用图：

执行：

Enter the connections of vertex 0:
1 0
Enter the connections of vertex 1:
0 2 3 4 1
Enter the connections of vertex 2:
1 2
Enter the connections of vertex 3:
1 4 3
Enter the connections of vertex 4:
1 3 4
The connection of vertex 0:
1 -> 0
The connection of vertex 1:
4 -> 3 -> 2 -> 0 -> 1
The connection of vertex 2:
1 -> 2
The connection of vertex 3:
4 -> 1 -> 3
The connection of vertex 4:
3 -> 1 -> 4
Enter the DFS starting node:0
(0, 1)
(1, 4)
(4, 3)
(1, 2)
Enter the BFS starting node:4
(4, 3)
(4, 1)
(1, 2)
(1, 0)