/************************ author's email:wardseptember@gmail.com date:2017.12.15 图的深度优先搜索遍历 ************************/
/* 图的深度优先搜索遍历类似于二叉树的先序遍历。它的基本思想是：首先访问出发点v,并将其标 记为已访问过；然后选取与v邻接的未被访问的任意一个顶点w,并访问它；再选取与w邻接的为被 访问的任一顶点并访问，以此重复进行。当一个顶点所有的邻接顶点都被访问过时，则依次退回 到最近被访问过的顶点，若该顶点还有其他邻接顶点未被访问，则从这些未被访问的顶点中去一 个并重复上述访问过程，直至图中所有顶点都被访问过为止。 */
#include<iostream>
#define maxSize 8
using namespace std;
typedef struct Node {   //定义一个结点
    int vertex;      //该边指向其他结点
    struct Node *pNext;   //指向下一条边的指针
}Node;
typedef struct head {//定义一个顶点
    char data;     //顶点的数据
    Node *first;    //指向第一条边的指针
}head, *Graph;
int visit[maxSize];       //定义一个全局变量，用来判断某一结点是否被访问过
Graph create_graph();    //创建一个邻接表
void DFS(Graph graph, int v); //深度遍历连通图
void dfs(Graph graph);       //深度遍历非连通图
void DFSTrave(Graph graph, int i, int j);//判断顶点i和顶点j（i!=j）之间是否有路径
int main() {
    Graph graph = create_graph();//接收一个邻接表
    cout << "深度遍历连通图结果为：";
    DFS(graph, 7);  //dfs(graph);深度遍历非连通图
    cout << endl;


    int i, j;
    cout << "请输入要判断的两个顶点(0-7):";
    cin >> i >> j;
    DFSTrave(graph, i, j);     //判断顶点i和顶点j（i!=j）之间是否有路径
    return 0;
    return 0;
}
Graph create_graph()
{
    //为保存顶点相关信息的数组分配空间，并对数据域赋值
    Graph graph = (Graph)malloc(maxSize * sizeof(head));
    int i;
    //顶点的序号按照输入顺序从0依次向后
    for (i = 0; i < maxSize; i++)
        graph[i].data = 'A' + i;

    //为每个节点对应的的单链表中的节点分配空间
    Node *p00 = (Node *)malloc(sizeof(Node));
    Node *p01 = (Node *)malloc(sizeof(Node));
    Node *p10 = (Node *)malloc(sizeof(Node));
    Node *p11 = (Node *)malloc(sizeof(Node));
    Node *p12 = (Node *)malloc(sizeof(Node));
    Node *p20 = (Node *)malloc(sizeof(Node));
    Node *p21 = (Node *)malloc(sizeof(Node));
    Node *p22 = (Node *)malloc(sizeof(Node));
    Node *p30 = (Node *)malloc(sizeof(Node));
    Node *p31 = (Node *)malloc(sizeof(Node));
    Node *p40 = (Node *)malloc(sizeof(Node));
    Node *p41 = (Node *)malloc(sizeof(Node));
    Node *p50 = (Node *)malloc(sizeof(Node));
    Node *p51 = (Node *)malloc(sizeof(Node));
    Node *p60 = (Node *)malloc(sizeof(Node));
    Node *p61 = (Node *)malloc(sizeof(Node));
    Node *p70 = (Node *)malloc(sizeof(Node));
    Node *p71 = (Node *)malloc(sizeof(Node));

    //为各单链表中的节点的相关属性赋值
    p00->vertex = 1;
    p00->pNext = p01;
    p01->vertex = 2;
    p01->pNext = NULL;
    p10->vertex = 0;
    p10->pNext = p11;
    p11->vertex = 3;
    p11->pNext = p12;
    p12->vertex = 4;
    p12->pNext = NULL;
    p20->vertex = 0;
    p20->pNext = p21;
    p21->vertex = 5;
    p21->pNext = p22;
    p22->vertex = 6;
    p22->pNext = NULL;
    p30->vertex = 1;
    p30->pNext = p31;
    p31->vertex = 7;
    p31->pNext = NULL;
    p40->vertex = 1;
    p40->pNext = p41;
    p41->vertex = 7;
    p41->pNext = NULL;
    p50->vertex = 2;
    p50->pNext = p51;
    p51->vertex = 6;
    p51->pNext = NULL;
    p60->vertex = 2;
    p60->pNext = p61;
    p61->vertex = 5;
    p61->pNext = NULL;
    p70->vertex = 3;
    p70->pNext = p71;
    p71->vertex = 4;
    p71->pNext = NULL;

    //将顶点与每个单链表连接起来
    graph[0].first = p00;
    graph[1].first = p10;
    graph[2].first = p20;
    graph[3].first = p30;
    graph[4].first = p40;
    graph[5].first = p50;
    graph[6].first = p60;
    graph[7].first = p70;

    return graph;
}
void DFS(Graph graph, int v) {//深度遍历连通图
    Node *p;                
    visit[v] = 1;         //置此结点已访问
    cout << graph[v].data<<' ';    //输出结点信息
    p = graph[v].first;    //p指向顶点v的第一条边
    while (p!=NULL) {       //p=NULL遍历结束
        if (visit[p->vertex] == 0)   //若此顶点未被访问，则递归访问他
            DFS(graph, p->vertex);
        p = p->pNext;   //p指向顶点v的下一条边的终点
    }
}
void dfs(Graph graph) {  //深度遍历非连通图
    int i;
    for (i = 0; i < maxSize; ++i)//循环使每个结点都访问到
        if (visit[i] == 0)
            DFS(graph, i);
}
void DFSTrave(Graph graph, int i, int j) {//判断顶点i和顶点j（i!=j）之间是否有路径
    int k;
    for (k = 0; k < maxSize; ++k)
        visit[k] = 0;
    DFS(graph, i);
    cout << endl;
    if (visit[j] == 1)//visit[j]=1则证明访问过程遇到了j
        cout << "两顶点间有路径" << endl;
    else
        cout << "两顶点间无路径" << endl;
}

以上如有错误，请指出，大家共同学习进步。