四、图的深度优先搜索算法

1、实验内容
1）编程实现图的深度优先算法。
2）修改算法，使之可以判断无向图有几个连通分量。
1、 实验要求
1） 通过实例，懂得深度优先搜索的机制。
2） 用2-3个实例验证算法。

GraphDFS C++算法：

<Graph.h>#include <iostream>#include<queue>//图的基本算法类封装实现//这里图用邻接表表示法（且是不带权的无向图）template <class ElemType>class CraphClass{public://图邻接表表示中节点数据结构typedf struct StructGraphNode{ElemType elem;struct StructGraphNode *next;}GraphNode, *GraphNodeLink;//图像遍历时节点颜色标记enum NodeColor{WHITE,//未被发现GRAY,//已被发现但是未访问BLACK//已被访问};static const int MaxVal = 99999;GraphClass();//默认构造函数~CraphClass()//析构函数//依据图中包含的节点以及邻接矩阵创建邻接表表示的图void createGraph(ElemType*a, int n, char *matrix);void BFSGraph();//图的广度优先搜索void DFSGraph();//图的深度优先搜索void _printAdjacencyList();//输出图的当前邻接表private:GraphNodeLink *root;//};

<Graph.cpp>#include <Graph.h>using namespace std;#define N 6#define INFINITE 0x7fffffff#define WHITE 1#define GRAY 2#define BLACK 3struct Vertex{Vertex * next;int id;Vertex() :next(NULL), id(0){}};struct Graph{Vertex *Adj[N + 1];int color[N + 1]; int p[N + 1];int d[N + 1];int f[N + 1];Graph(){for (int i = 1; i <= N; i++){Adj[i] = new Vertex;color[i] = WHITE;d[i] = 0;f[i] = 0;p[i] = 0;}}~Graph(){for (int i = 1; i <= N; i++)delete Adj[i];}};void Print(Graph *g);bool Init(Graph *g);bool InsertEdge(Graph *g, int start, int end);void PaintColor(Graph *g, int vertex, int color);void DepthFirstVisit(Graph *g, int vertex, int& v_time);//插入边bool InsertEdge(Graph *g, int start, int end){Vertex* v = new Vertex();v->id = end;if (g->Adj[start]->next == NULL){Vertex* s = new Vertex();s->id = start;g->Adj[start] = s;}Vertex* tmp = g->Adj[start];while (tmp->next){tmp = tmp->next;}tmp->next = v;return true;}bool graph(Graph *g){InsertEdge(g, 1, 2);InsertEdge(g, 1, 4);InsertEdge(g, 2, 5);InsertEdge(g, 3, 5);InsertEdge(g, 3, 6);InsertEdge(g, 4, 2);InsertEdge(g, 5, 4);InsertEdge(g, 3, 1);InsertEdge(g, 6, 6);return true;}bool DepthFirstSearch(Graph *g, int vertex){for (int i = 1; i <= N; i++){g->color[i] = WHITE;}int time = 0;for (int i = 1; i <= N; i++){if (g->color[i] == WHITE){DepthFirstVisit(g, i, time);}}return true;}void DepthFirstVisit(Graph *g, int vertex, int& v_time){g->color[vertex] = GRAY;v_time++;g->d[vertex] = v_time;Vertex * v = g->Adj[vertex];int node = v->id;std::cout << node << "\t";v = v->next;while (v){if (g->color[v->id] == WHITE){g->p[v->id] = vertex;DepthFirstVisit(g, v->id, v_time);}v = v->next;}g->color[node] = BLACK;g->f[node] = v_time++;}int main(){Graph *g = new Graph;graph(g);DepthFirstSearch(g, 1);getchar();return 0;}

GraphDFS java 算法：

package exercise04;public class DFS {public static void main(String[] args) {int [][]c = new int[9][9];for(int i = 0;i < c.length;i++){for(int j = 0;j < c[0].length;j++){c[i][j] = 0;}}c[1][2] = c[2][1] = 1;c[1][3] = c[3][1] = 1;c[2][4] = c[4][2] = 1;c[2][5] = c[5][2] = 1;c[3][6] = c[6][3] = 1;c[3][7] = c[7][3] = 1;c[4][8] = c[8][4] = 1;c[5][8] = c[8][5] = 1;c[6][7] = c[7][6] = 1;System.out.println("The c :");for(int i = 1;i < c.length;i++){for(int j = 1;j < c.length;j++){System.out.print(c[i][j] + " ");}System.out.println();}System.out.println("the count = " + DFSSearch(c));}public static int DFSSearch(int [][]c){int []visited = new int[c.length];for(int i = 0;i < c.length;i++){visited[i] = 0;}for(int i = 1;i < c.length;i++){if(visited[i] == 0){DFS(c,i,visited);visited[0]++;}}return visited[0];}public static void DFS(int [][]c,int v,int []visited){System.out.println("visit : " + v);visited[v] = 1;int w = getFirstNeibor(c,v,visited);while(w != -1){if(visited[w] == 0){DFS(c,w,visited);}else{w = getNextNeibor(c,v,w,visited);}}}public static int getFirstNeibor(int [][]c,int v,int []visited){for(int i = 0;i < c.length;i++){if(c[i][v] == 1 && visited[i] == 0){return i;}}return -1;}public static int getNextNeibor(int [][]c,int v,int w,int []visited){for(int i = 0;i < c.length;i++){if(c[i][v] == 1 && i != w && visited[i] == 0){return i;}}return -1;}}