/* 圖形的追蹤: 相鄰串列與廣度優先搜尋法(BFS)*/
#include <stdio.h>
#include <stdlib.h>
#define MAX_V 100  /*最大節點數*/
#define TRUE 1
#define FALSE 0

/*定義資料結構*/
typedef struct node_tag {
    int vertex;
    struct node_tag *link;
} Node;

/*定義佇列結構*/
typedef struct {
    int items[MAX_V];
    int front;
    int rear;
} Queue;

Node *adjlist[MAX_V+1];  /*宣告相鄰串列*/
int visited[MAX_V+1];    /*記錄頂點是否已拜訪*/
int total_vertex;

void build_adjlist(void);
void show_adjlist(void);
void bfs(int);
Node *searchlast(Node *);

/*佇列操作函數*/
Queue* createQueue() {
    Queue *q = (Queue*)malloc(sizeof(Queue));
    q->front = -1;
    q->rear = -1;
    return q;
}

int isEmpty(Queue* q) {
    return q->front == -1;
}

void enqueue(Queue* q, int value) {
    if(q->front == -1)
        q->front = 0;
    q->rear++;
    q->items[q->rear] = value;
}

int dequeue(Queue* q) {
    int item = q->items[q->front];
    if(q->front == q->rear) {
        q->front = -1;
        q->rear = -1;
    } else {
        q->front++;
    }
    return item;
}

int main()
{
    build_adjlist(); /*以相鄰串列表示圖形*/
    show_adjlist();  /*顯示串列之資料*/
    puts("\n------Breadth First Search------");
    bfs(1);          /*圖形之廣度優先搜尋，以頂點1為啟始頂點*/
    printf("\n");
    return 0;
}

void build_adjlist()
{
    FILE *fptr;
    Node *node,*lastnode;
    int vi,vj ,weight;
    fptr = fopen("dfs_1.dat", "r");
    if (fptr == NULL) {
        perror("dfs.dat");
        exit(0);
    }
    /* 讀取節點總數 */
    fscanf(fptr, "%d", &total_vertex);
    for (vi = 1; vi <= total_vertex; vi++) {
        /*設定陣列及各串列啟始值*/
        visited[vi] = FALSE;
        adjlist[vi] = (Node *)malloc(sizeof(Node));
        adjlist[vi]->vertex = vi;
        adjlist[vi]->link = NULL;
    }
    /* 讀取節點資料 */
    for (vi = 1; vi <= total_vertex; vi++)
        for (vj = 1; vj <= total_vertex; vj++) {
            fscanf(fptr,"%d",&weight);
            /* 資料檔以相鄰矩陣格式儲存,以1代表相鄰
               0 代表不相鄰，將相鄰頂點鏈結在各串列後 */
            if (weight != 0) {
                node = (Node *)malloc(sizeof(Node));
                node->vertex = vj;
                node->link = NULL;
                lastnode = searchlast(adjlist[vi]);
                lastnode->link = node;
            }
        }
    fclose(fptr);
}

/*顯示各相鄰串列之資料*/
void show_adjlist()
{
    int index;
    Node *ptr;
    puts("Head    adjacency nodes");
    puts("------------------------------");
    for (index = 1; index <= total_vertex; index++) {
        printf("V%-2d ",adjlist[index]->vertex);
        ptr = adjlist[index]->link;
        while (ptr != NULL) {
            printf("--> V%d ",ptr->vertex);
            ptr = ptr->link;
        }
        printf("\n");
    }
}

/*圖形之廣度優先搜尋*/
void bfs(int start)
{
    Queue* q = createQueue();
    Node* ptr;
    
    // 將起始節點加入佇列
    enqueue(q, start);
    visited[start] = TRUE;
    
    while(!isEmpty(q)) {
        // 從佇列取出節點並印出
        int currentVertex = dequeue(q);
        printf("V%d ", currentVertex);
        
        // 將所有相鄰且未拜訪的節點加入佇列
        ptr = adjlist[currentVertex]->link;
        while(ptr != NULL) {
            if(!visited[ptr->vertex]) {
                enqueue(q, ptr->vertex);
                visited[ptr->vertex] = TRUE;
            }
            ptr = ptr->link;
        }
    }
    
    free(q);
}

/*搜尋串列最後節點函數*/
Node *searchlast(Node *linklist)
{
    Node *ptr;
    ptr = linklist;
    while (ptr->link != NULL)
        ptr = ptr->link;
    return ptr;
}