1.递归

void DFS(ALGraph G, int v)
{
    visited[v] = 1;
    printf("%c ", G.vertices[v].data);

    for (ArcNode* cur = G.vertices[v].firstarc; cur != nullptr; cur = cur->nextarc)
    {
        if (!visited[cur->adjvex])
            DFS(G, cur->adjvex);
    }
}

2.非递归

#include <stack>
#include <iostream>
using namespace std;
void DFS(ALGraph G, int v)
{
    visited[v] = 1;
    printf("%c ", G.vertices[v].data);

    stack<ArcNode*> st;
    ArcNode* cur = G.vertices[v].firstarc;
    int index = 0;
    while (cur || !st.empty())
    {
        while (cur)
        {
            index = cur->adjvex;
            if (!visited[index])
            {
                st.push(cur);
                visited[index] = 1;
                printf("%c ", G.vertices[index].data);
                cur = G.vertices[index].firstarc;
            }
            else
                cur = cur->nextarc;
        }
        if(st.empty())
            break;
        cur = st.top();
        st.pop();
        cur = cur->nextarc;
    }
}