广度优先遍历最主要的是 利用队列的数据结构。

#include <stdio.h>
#include <stdlib.h>



#define VertexNum 9
struct BFS_Node
{
	int v;
	struct BFS_Node *next;
};
typedef struct BFS_Node *Graph;
struct BFS_Node BFS_Head[VertexNum];
int g_bfs_visited[VertexNum];

int g_queue[VertexNum];
int front = -1;
int rear = -1;

void bfs_create_graph(int v1, int v2)
{
	Graph pointer;
	Graph New = (Graph)malloc(sizeof(struct BFS_Node));
	if (New != NULL)
	{
		New->v = v2; /*临近节点*/
		New->next = NULL;

		pointer = &(BFS_Head[v1]);
		while(pointer->next !=NULL)
			pointer = pointer->next;
		pointer->next = New;
	}
}

void bfs_print_graph(struct BFS_Node *BFS_Head)
{
	Graph pointer;
	pointer = BFS_Head->next;
	while (pointer!=NULL)
	{
		printf("[%d]", pointer->v);
		pointer = pointer->next;
	}
	printf("\n");
}

int dequeue()
{
	if (front == rear)/*empty*/
		return -1;
	else
	{
		front++;
		return g_queue[front];
	}
}

int enqueue(int v)
{
	if (rear >= VertexNum+1)/*Full*/
		return -1;
	else
	{
		rear++;/*队列尾端指针后移*/
		g_queue[rear] = v;
		return 1;
	}
}
void BFS(int v)
{
	Graph pointer;
	g_bfs_visited[v] = 1; /*已经查找过了*/
	enqueue(v);
	printf("[%d]==>", v);

	while (front != rear)
	{
		v = dequeue();
		
		pointer = BFS_Head[v].next;
	
		while(pointer != NULL)
		{
			if (g_bfs_visited[pointer->v] == 0)
			{
				enqueue(pointer->v);
				g_bfs_visited[pointer->v] = 1;
				printf("[%d]==>", pointer->v);
			}
			pointer = pointer->next;
		}
	}

}
int main(int argc, char **argv)
{
	int i = 0;
	int BFS_Node[20][2] = {
		{1,2}, {2,1}, {1,3}, {3,1},
		{2,4}, {4,2}, {2,5}, {5,2},
		{3,6}, {6,3}, {3,7}, {7,3},
		{4,8}, {8,4}, {5,8}, {8,5},
		{6,8}, {8,6}, {7,8}, {8,7}
	};

	for (i = 0; i < VertexNum; i++)
	{
		BFS_Head[i].v = i;
		BFS_Head[i].next = NULL;
		g_bfs_visited[i] = 0;
	}

	for(i = 0; i < 20; i++)
	{
		bfs_create_graph(BFS_Node[i][0], BFS_Node[i][1]);
	}
	printf("++ Graph ++\n");
	for (i = 0; i< VertexNum; i++)
	{
		printf("Ver[%d] : ", i);
		bfs_print_graph(&BFS_Head[i]);
	}
	printf("Bradth-First-Search : \n");
	printf("[Begin]==>");
	BFS(1);
	printf("[End]");

	return 0;
}