广度优先搜索(BFS)

图形:

 邻接矩阵：

        两点之间有边则设为1。

代码实现： 

#include 
#include 

#define MAX_SIZE 8

typedef int Status;

Status graph[8][8] = {
//   A  B  C  D  E  F  G  H
    {0, 1, 1, 1, 0, 0, 0, 0}, // A
    {1, 0, 1, 0, 1, 0, 0, 0}, // B
    {1, 1, 0, 1, 1, 0, 0, 1}, // C
    {1, 0, 1, 0, 0, 1, 1, 0}, // D
    {0, 1, 1, 0, 0, 0, 0, 1}, // E
    {0, 0, 0, 1, 0, 0, 0, 1}, // F
    {0, 0, 0, 1, 0, 0, 0, 1}, // G
    {0, 0, 1, 0, 1, 1, 1, 0}, // H
};

typedef char ElemType;

typedef struct Queue
{
    ElemType *head, *rear;
} Queue;

void initQueue(Queue *Q)
{
    Q->head = (ElemType *)malloc(MAX_SIZE * sizeof(ElemType));
    if ( !Q->head )
    {
        printf("init defeat!\n");
    }
    Q->rear = Q->head;
}

void printPoint(Queue *Q)
{
    printf(">> ");
    int row;
    ElemType *tmp = Q->head;
    while ( tmp != Q->rear )
    {
        row = *(tmp);
        printf("%c ", row);
        for (int i = 0; i < 8; i++)
        {
            if ( 1 == graph[row-65][i] )
            {
                *(Q->rear) = i+65;
                Q->rear ++;
                for (int j = 0; j < 8; j++)
                {
                    graph[j][i] = 0;    // 标记已走过的点
                }
            }
        }
        tmp ++;
    }
}

void destoryQueue(Queue *Q)
{
    free(Q->head);
}

int main(void)
{
    char start;
    Queue queue;
    initQueue(&queue);
    printf("Input start point:");
    scanf("%c", &start);
    *(queue.rear) = start;
    queue.rear ++;
    for (int i = 0; i < 8; i++)
    {
        graph[i][start-65] = 0;
    }
    printPoint(&queue);
    destoryQueue(&queue);
    return 0;
}

运行结果：

        Input start point:A
        >> A B C D E H F G

        Input start point:B
        >> B A C E D H F G