#include <iostream>
#include <queue>
#include <stack>


using namespace std;


/***************************************
 *  * 图的深度优先遍历
 *   * 基于邻接链表的非递归实现
 *    **************************************/


typedef char vertex_t;  //结点数据类型


//边结点
typedef struct _tag_edge_node_t
{
    int node_num;  //边终点所在数组序号
    _tag_edge_node_t* next_node;  //下一条边
}edge_node_t;


//顶点结点
typedef struct _tag_head_node_t
{
    vertex_t data;  //结点数据
    edge_node_t* first_edge;  //第一条边
}head_node_t;


#define MAX_NUMBER 20  //图中最大结点数目


//图结构
typedef struct _tag_graph_t
{
    head_node_t head_data[MAX_NUMBER];  //顶点数组
    unsigned int head_node_count;  //顶点数目
}graph_t;


void create_adjacency_list(graph_t* graph)
{
    edge_node_t* p_edge = NULL;
    if (graph == NULL)
        return;


    graph->head_node_count = 6;
    for (unsigned int i = 0; i < graph->head_node_count; ++i)
    {
        graph->head_data[i].data = 'A' + i;
        graph->head_data[i].first_edge = NULL;
    }


    graph->head_data[0].first_edge = new edge_node_t;
    p_edge = graph->head_data[0].first_edge;
    p_edge->node_num = 2;

    p_edge->next_node = new edge_node_t;
    p_edge = p_edge->next_node;
    p_edge->node_num = 4;


    p_edge->next_node = new edge_node_t;
    p_edge = p_edge->next_node;
    p_edge->node_num = 5;
    p_edge->next_node = NULL;


    graph->head_data[1].first_edge = new edge_node_t;
    graph->head_data[1].first_edge->node_num = 2;
    graph->head_data[1].first_edge->next_node = NULL;


    graph->head_data[2].first_edge = new edge_node_t;
    graph->head_data[2].first_edge->node_num = 3;
    graph->head_data[2].first_edge->next_node = NULL;


    graph->head_data[3].first_edge = new edge_node_t;
    graph->head_data[3].first_edge->node_num = 5;
    graph->head_data[3].first_edge->next_node = NULL;


    graph->head_data[4].first_edge = new edge_node_t;
    graph->head_data[4].first_edge->node_num = 1;
    graph->head_data[4].first_edge->next_node = 
        new edge_node_t;

    p_edge = graph->head_data[4].first_edge->next_node;
    p_edge->node_num = 3;
    p_edge->next_node = new edge_node_t;

    p_edge = p_edge->next_node;
    p_edge->node_num = 5;
    p_edge->next_node = NULL;
}

void breadth_first_search(graph_t *graph, int start_pos)
{
    queue<int> visit_queue;  //访问队列
    bool is_visit[MAX_NUMBER];  //访问标志数组
    for (int i = 0; i < MAX_NUMBER; ++i)
        is_visit[i] = false;

    for (unsigned int i = 0; i < graph->head_node_count; 
            ++i)
    {
        if (!is_visit[i])  //该结点没有被访问
            visit_queue.push(i);

        while (!visit_queue.empty())
        {
            //出队
            int n_pos = visit_queue.front();
            visit_queue.pop();
            if (!is_visit[n_pos])
            {
                cout<<graph->head_data[n_pos].data<<endl;
                is_visit[n_pos] = true;

                //将该结点下所有未被访问的边入队
                edge_node_t *next = 
                    graph->head_data[n_pos].first_edge;
                while (next != NULL)
                {
                    if (!is_visit[next->node_num])
                        visit_queue.push(next->node_num);
                    next = next->next_node;
                }
            }
        }
    }
}

void depth_first_search(graph_t* graph, int start_pos)
{
    stack<int> visit_node;
    bool is_visit[MAX_NUMBER];  //访问标志数组
    for (int i = 0; i < MAX_NUMBER; ++i)
        is_visit[i] = false;


    cout<<graph->head_data[start_pos].data<<endl;
    is_visit[start_pos] = true;
    visit_node.push(start_pos);  //将第一个元素压栈
    while (!visit_node.empty())
    {
        int num = visit_node.top();
        edge_node_t* next = graph->head_data[num].first_edge;
        for (; next != NULL; next = next->next_node)  //存在边，且该边的终点未被访问
        {
            if (!is_visit[next->node_num])
            {
                cout<<graph->head_data[next->node_num].data<<endl;
                is_visit[next->node_num] = true;
                visit_node.push(next->node_num);
                break;
            }
        }
        if (next == NULL)  //以该结点为起点的所有终点访问完毕
            visit_node.pop();
    }
}

int main(int argc, char* argv[])
{
    graph_t graph;
    create_adjacency_list(&graph);
    //depth_first_search(&graph, 0);
    breadth_first_search(&graph, 0);
    return 0;
}