邻接表实现图的深度遍历

邻接表实现图的深度遍历，纠结的问题啊。。。。。

#include <stdio.h>
#include <malloc.h>
#define MAX 100
typedef struct arcnode/*表节点*/
{
    int adjvex; /*邻接点*/
    struct arcnode *nextarc;/*指向下一条弧的指针*/
}arcnode;
typedef struct vnode /*头结点*/
{
    int data; /*定点信息*/
    arcnode * firstarc; /*指向第一个依附该顶点的弧的指针*/
}vnode, adjlist[MAX];
typedef struct  /*图*/
{
    adjlist vertices;   /*顶*/
    int vexnum, arcnum;  /*图的顶点数和弧数*/
}algraph;

int visited[MAX];
int n = 1;

int locateVex(algraph * g, int v) /*寻找节点V的位置*/
{
    int k, n;
    for(k = 1; k <= g->vexnum; k++)
    {
        if(g->vertices[k].data == v)
        {
            n = k;
            break;
        }
    }
    return n;
}

void Insertadj(algraph * g, int i, int j) /*插入邻接点的下标*/
{
    arcnode *a1, *a2;
    a1 = (arcnode *)malloc(sizeof(arcnode));
    a1->adjvex = j; a1->nextarc = NULL;
    if(g->vertices[i].firstarc == NULL)
    {
        g->vertices[i].firstarc = a1;
    }
    else
    {
        a2 = g->vertices[i].firstarc;
        while(a2->nextarc)
        {
            a2 = a2->nextarc;
        }
        a2->nextarc = a1;
    }
}
void Print_algraph(algraph * g) /*打印邻接表*/
{
    int i;
    arcnode *a3;
    for(i = 1; i<= g->vexnum; i++)//打印无向图邻接表
    {
        printf(" %d V%d |", i, g->vertices[i].data);
        if(g->vertices[i].firstarc != NULL)
        {
            a3 = g->vertices[i].firstarc;
            while(a3)
            {
                printf(" --> %d ", a3->adjvex);
                a3 = a3->nextarc;
            }
        }
        printf("\n");
    }
}

void Init_algraph(algraph * g) /*初始化图并建图*/
{
    int v, v1, v2, i, j;
    scanf("%d %d",&g->vexnum, &g->arcnum);//输入(点,边)
    for(v = 1; v <= g->vexnum; v++)
    {
        scanf("%d", &g->vertices[v].data);//输入点 V
        g->vertices[v].firstarc = NULL;
    }
    for(v = 1; v <= g->arcnum; v++)
    {
        scanf("%d %d", &v1, &v2);//输入(点,点),即边
        i = locateVex(g,v1);  /*v1的位置*/
        j = locateVex(g,v2);  /*v2的位置*/
        Insertadj(g,i,j);
        Insertadj(g,j,i);
    }
    Print_algraph(g);
}
void DFS(algraph * g, int v)
{
    arcnode * p;
    p = g->vertices[v].firstarc;
    if(n < g->vexnum)
    {
        printf(" V%d -->",g->vertices[v].data);
        n++;
    }
    else
        printf(" V%d\n", g->vertices[v].data);
    visited[v] = 1;
    while(p)
    {
        if(!visited[p->adjvex])
        DFS(g,p->adjvex);
        p = p->nextarc;
    }
}
void DFSvisit(algraph *g)//深度优先遍历点顺序
{
    int v;
    printf("\nDepth_first search:\n");
    for(v = 1; v <= g->vexnum; v++)
        visited[v] = 0;
    for(v = 1; v <= g->vexnum; v++)
        if(!visited[v])
            DFS(g,v);
}
int main()
{
    algraph g;
    Init_algraph(&g);
    DFSvisit(&g);
    return 0;
}