【HDOJ】1180 诡异的楼梯

bfs+优先队列。wa了N次，才发现可以停留等待楼梯变换方向。

#include <iostream>
#include <queue>
#include <cstdio>
#include <cstring>
using namespace std;

#define MAXNUM 55

typedef struct node_st {
    int x, y, t;
    node_st() {}
    node_st(int xx, int yy, int tt) {
        x = xx; y = yy; t = tt;
    }
    friend bool operator < (node_st a, node_st b) {
        return a.t > b.t;
    }
} node_st;

char map[MAXNUM][MAXNUM];
char visit[MAXNUM][MAXNUM];
int n, m;
int begx, begy, endx, endy;
int direct[4][2] = {{1,0},{-1,0},{0,1},{0,-1}};

int bfs(int begx, int begy) {
    priority_queue<node_st> que;
    node_st node;
    int i, x, y, nx, ny, t;

    que.push(node_st(begx, begy, 0));
    memset(visit, 0, sizeof(visit));
    visit[begx][begy] = 1;

    while ( !que.empty() ) {
        node = que.top();
        if (map[node.x][node.y] == 'T') {
            return node.t;
        }
        que.pop();
        for (i=0; i<4; ++i) {                
            x = node.x + direct[i][0];
            y = node.y + direct[i][1];
            if (x<0 || x>=n || y<0 || y>=m)
                continue;
            if (visit[x][y] || map[x][y] == '*')
                continue;
            if (map[x][y] == '.' || map[x][y]=='T') {
                que.push(node_st(x,y,node.t+1));
                visit[x][y] = 1;
                continue;
            }
            if (map[x][y]=='|' || map[x][y]=='-') {
                nx = x + direct[i][0];
                ny = y + direct[i][1];
                t = node.t + 1;
                if (nx<0 || nx>=n || ny<0 || ny>=m)
                    continue;
                if (visit[nx][ny] || map[nx][ny]=='*')
                    continue;
                if ( ((map[x][y]=='|') && ((node.t&1)==0) && (i==2||i==3)) ||
                     ((map[x][y]=='|') && ((node.t&1)!=0) && (i==0||i==1)) ||
                     ((map[x][y]=='-') && ((node.t&1)==0) && (i==0||i==1)) ||
                     ((map[x][y]=='-') && ((node.t&1)!=0) && (i==2||i==3)) )
                     ++t;
                visit[nx][ny] = 1;
                que.push(node_st(nx, ny, t));
            }
        }
    }

    return -1;
}

int main() {
    int i, j;

    while (scanf("%d %d%*c",&n,&m) != EOF) {
        for (i=0; i<n; ++i) {
            scanf("%s", map[i]);
            for (j=0; j<m; ++j) {
                if (map[i][j] == 'S') {
                    begx = i;
                    begy = j;
                }
            }
        }
        i = bfs(begx, begy);
        printf("%d
", i);
    }

    return 0;
}