BFS(基于C语言的简单实现)_bfs代码实现c语言

BFS(基于C语言的简单实现)

• 把根结点放到队列的末尾

• 每次从队列的头部取出一个元素，查看这个元素所有的下一级元素，把它们放到队列的末尾。并把这个元素标记为它下一级元素的前驱

• 找到所要找的元素时结束程序

• 如果遍历整个树都还没有找到，则结束程序

#include<stdio.h>
#include<stdlib.h>
#define MAX_VALUE 4
int visit[MAX_VALUE];
typedef struct ArcNode
{
	int adjvex;
	struct ArcNode*nextarc;
}ArcNode;
typedef struct VNode
{
	int data;
	ArcNode*firstarc;
}VNode,AdjList[MAX_VALUE];
typedef struct
{
	AdjList vertices;
	int vexnum, arcnum;
}ALGraph;
typedef struct queue
{
	int *pBase;
	int front, rear;
}QUEUE;
int LocateVex(ALGraph G, int v);
void CreatUDG(ALGraph *G);
void PrintUDG(ALGraph G);
void init_queue(QUEUE*Q);
bool isfull_queue(QUEUE*Q);
bool isempty_queue(QUEUE*Q);
void in_queue(QUEUE*Q,int val);
int out_queue(QUEUE*Q);
void BFS(ALGraph G,QUEUE*Q);
void BFST(ALGraph G, QUEUE *Q);
int main()
{
	ALGraph G;
	QUEUE Q;
	CreatUDG(&G);
	PrintUDG(G);
	BFST(G, &Q);
	return 0;
}
int LocateVex(ALGraph G, int v)
{
	for (int i = 0; i < G.vexnum; i++)
	{
		if (G.vertices[i].data == v)
		{
			return i;
		}
	}
}
void CreatUDG(ALGraph *G)
{
	ArcNode*p, *q;
	int i, j, v1, v2;
	printf("分别输入顶点个数和边的个数：\n");
	scanf("%d%d", &(G->vexnum), &(G->arcnum));
	printf("请输入各个顶点的值：\n");
	for (int i = 0; i < G->vexnum; i++)
	{
		scanf("%d", &(G->vertices[i].data));
		G->vertices[i].firstarc = NULL;
	}
	printf("分别输入各条边的两个顶点：\n");
	for (int k = 0; k < G->arcnum; k++)
	{
		scanf("%d%d", &v1, &v2);
		i = LocateVex(*G, v1);
		j = LocateVex(*G, v2);
		p = (ArcNode*)malloc(sizeof(ArcNode));
		p->adjvex = j;
		p->nextarc = NULL;
		p->nextarc = G->vertices[i].firstarc;
		G->vertices[i].firstarc = p;
		q = (ArcNode*)malloc(sizeof(ArcNode));
		q->adjvex = i;
		q->nextarc = NULL;
		q->nextarc = G->vertices[j].firstarc;
		G->vertices[j].firstarc = q;
	}
}
void PrintUDG(ALGraph G)
{
	ArcNode*p = NULL;
	for (int i = 0; i < G.vexnum; i++)
	{
		printf("第%d条边\n", i + 1);
		p = G.vertices[i].firstarc;
		while (p != NULL)
		{
			printf("%d  ", (p->adjvex) + 1);
			p = p->nextarc;
		}
		printf("\n");
	}
}
void init_queue(QUEUE*Q)
{
	Q->pBase = (int*)malloc((sizeof(int))*4);
	Q->front = 0;
	Q->rear = 0;
}
bool isfull_queue(QUEUE*Q)
{ 
	if (((Q->rear + 1) % MAX_VALUE) == Q->front)
	{
		return true;
	}
	else
		return false;
}
bool isempty_queue(QUEUE*Q)
{
	if (Q->rear == Q->front)
	{
		return true;
	}
	else
		return false;
}
void in_queue(QUEUE*Q, int val)
{
	if (isfull_queue(Q))
	{
		return;
	}
	Q->pBase[Q->rear] = val;
	Q->rear = (Q->rear + 1) % MAX_VALUE;
	//printf("入对元素为%d\n", val);
}
int out_queue(QUEUE*Q)
{
	int temp = 0;
	if (isempty_queue(Q))
		return 0;
	temp = Q->pBase[Q->front];
	Q->front = (Q->front + 1) % MAX_VALUE;
	//printf("\n返回的值为%d\n", temp);
	return temp;
}
void BFS(ALGraph G,QUEUE*Q)
{
	init_queue(Q);
	//自己总结：  注意  下面的这两条语句要放在开头或者在下面的for循环里面在加上条件
	//判断visit数组是否访问过  否则就会当while循环退出的时候 就会继续执行printf("%d  ", G.vertices[i].data)
	//会导致多输出结果
	visit[0] = 1;
	printf("%d  ", G.vertices[0].data);
	for (int i = 0; i < G.vexnum; i++)
	{
		//visit[i] = 1;
		//printf("%d  ", G.vertices[i].data);
		in_queue(Q,i);
		while (!isempty_queue(Q))
		{
			int temp=out_queue(Q);
			ArcNode*p = G.vertices[temp].firstarc;
			while (p!=NULL)
			{
				if (visit[p->adjvex]==0)
				{
					visit[p->adjvex] = 1;
					printf("%d  ", G.vertices[p->adjvex].data);
					in_queue(Q, p->adjvex);
				}
				p = p->nextarc;
			}
		}
	}
}
void BFST(ALGraph G, QUEUE *Q)
{
	for (int i = 0; i < G.vexnum; i++)
	{
		if (!visit[i])
		{
			BFS(G, Q);
		}
	}
}