经典算法之图的深度优先搜索遍历

/************************author's email:[e-mail]: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 8using 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;}

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