C语言BFS模板

广度优先算法对于求解最优解问题方面，应用广泛，现给出常用模板用于参考：

#define MAX_MN 300
#define MAX_STORE_NUM 90000
#define MAX_DIRECTION_NUM 4
typedef struct {
    int x;
    int y;
} PosStr;

#define MAX_ROW 50
#define MAX_COL 50
#define MAX_NUM MAX_ROW * MAX_COL
#define MAX_DIR_NUM 4
int direction[MAX_DIR_NUM][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};

int NearestWareHouse(int **arr, int m, int n)
{
    int ret = 0;
    PosStr queue[MAX_STORE_NUM] = {0};
    memset(queue, 0, sizeof(PosStr) * MAX_STORE_NUM);
    int head = 0;
    int tail = 0;
    int vis[MAX_MN][MAX_MN] = {0};
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (arr[i][j] == 0) {
                queue[tail].x = i;
                queue[tail].y = j;
                tail++;
            }
        }
    }
    int dis = 0;
    while (head < tail) {
        int len = tail - head;
        for (int i = 0; i < len; i++) {
            PosStr temp = queue[head++];
            for (int j = 0; j < MAX_DIRECTION_NUM; j++) {
                int nextx = temp.x + direction[j][0];
                int nexty = temp.y + direction[j][1];
                if (nextx < 0 || nextx >= m || nexty < 0 || nexty >= n || arr[nextx][nexty] != 1 || vis[nextx][nexty] == 1) {
                    continue;
                }
                queue[tail].x = nextx;
                queue[tail++].y = nexty;
                ret += (dis + 1);
                vis[nextx][nexty] = 1;
            }
        }
        dis++;
    }
    return ret;
}