POJ 2251 Dungeon Master

习惯用双广了，这次WA了好几次，标记起和终止始节点时发现了错误，后来没改彻底，具体见注释行。

双广速度快，空间小，结构也相对 bfs 简单；

# include <stdio.h>
# include <string.h>

typedef struct {char l, r, c;}Pos;  /* char 足够了，比较时没出错 */

const int dir[][3] = {{0,0,1}, {0,0,-1}, {0,1,0}, {0,-1,0}, {1,0,0}, {-1,0,0}};

Pos start, goal;
char L, R, C;
char dun[35][35][35];
char vis[35][35][35];
short dis[35][35][35];

char read_data(void)
{
    char f1, f2;
    int i, j, k;
    
    if (~scanf("%d%d%d", &L, &R, &C)) return 0;
    if (L==0 && R==0 && C==0) return 0;
    f1 = f2 = 1;
    for (i = 1; i <= L; ++i)
    for (j = 1; j <= R; ++j)
    {
        scanf("%s", dun[i][j]+1);
        for (k = 1; f1 && k<=C; ++k)
            if (dun[i][j][k] == 'S')
            {
                f1 = 0;
                start.l = i;      /* WA: start.l = 1 */
                start.r = j;
                start.c = k;
                break;
            }
        for (k = 1; f2 && k<=C; ++k)
            if (dun[i][j][k] == 'E')
            {
                f2 = 0;
                goal.l = i;   /* WA: goal.l = L */
                goal.r = j;
                goal.c = k;
                break;
            }
    }
    
    return 1;
}

int bfs(void)
{
    Pos Q[30000], cur, nst;
    char nl, nr, nc;
    int front, rear, i;
    
    memset(vis, 0, sizeof(vis));  /* WA vis必须要清空，dis则不是必须的 */
    
    front = 1;
    rear = 3;
    
    Q[1] = start;
    Q[2] = goal;
    
    vis[start.l][start.r][start.c] = 1;
    vis[ goal.l][ goal.r][ goal.c] = 2;
    
    dis[start.l][start.r][start.c] = 0;
    dis[ goal.l][ goal.r][ goal.c] = 0;
    
    while (front < rear)
    {
        cur = Q[front++];
        for (i = 0; i < 6; ++i)
        {
            nl = cur.l + dir[i][0];
            nr = cur.r + dir[i][1];
            nc = cur.c + dir[i][2];
            if (1<=nl&&nl<=L && 1<=nr&&nr<=R && 1<=nc&&nc<=C && dun[nl][nr][nc]!='#')
            {
                if (!vis[nl][nr][nc])
                {                    
                    nst.l = nl, nst.r = nr, nst.c = nc;
                    Q[rear++] = nst;
                    vis[nl][nr][nc] = vis[cur.l][cur.r][cur.c];
                    dis[nl][nr][nc] = dis[cur.l][cur.r][cur.c] + 1;
                }
                else if (vis[cur.l][cur.r][cur.c] != vis[nl][nr][nc])
                {
                    return dis[cur.l][cur.r][cur.c] + dis[nl][nr][nc] + 1;
                }
            }
        }
    }
    
    return -1;
}

void solve(void)
{
    int ans;
    
    ans = bfs();
    if (ans == -1) puts("Trapped!");
    else printf("Escaped in %d minute(s).\n", ans);
}

int main()
{
    while (read_data())
    {
        solve();
    }
    
    return 0;
}

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