ACM/ICPC 之 靠墙走-DFS+BFS(POJ3083)

 

//POJ3083
//DFS求靠左墙(右墙)走的路径长+BFS求最短路
//Time:0Ms  Memory:716K
#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
using namespace std;

#define MAX 45
#define INRANGE(x,y) (x >= 0 && x < n && y >=0 && y < m)

struct Point{
    int x, y, d;
    Point(int xx,int yy,int dd):x(xx), y(yy), d(dd){}
};

int n,m;
int sx,sy;
char mize[MAX][MAX];
bool vis[MAX][MAX];
int mov[4][2] = {{0,1},{1,0},{0,-1},{-1,0}};    //东南西北

int dfs(int x, int y, int f, int c)
{
    if(mize[x][y] == 'E') return 1;
    int px = x + mov[(f+c)%4][0], py = y + mov[(f+c)%4][1]; //左侧(右侧)
    int fx = x + mov[f][0], fy = y + mov[f][1]; //前侧
    if(mize[px][py] == '.' || mize[px][py] == 'E')
    {
        f = (f+c)%4;    //向左转(向右转)
        fx = x + mov[f][0], fy = y + mov[f][1];
    }
    while(mize[fx][fy] == '#')
    {
        f = (f+4-c)%4;  //向右转(向左转)
        fx = x + mov[f][0], fy = y + mov[f][1];
    }
    return 1 + dfs(fx,fy,f,c);
}

int bfs(int x, int y)
{
    memset(vis,false, sizeof(vis));
    queue<Point> q;
    q.push(Point(x,y,1));
    vis[x][y] = true;
    while(!q.empty()){
        Point cur = q.front();
        q.pop();
        for(int i =0; i < 4;i++)
        {
            int tx = cur.x + mov[i][0];
            int ty = cur.y + mov[i][1];
            if(INRANGE(tx,ty) && mize[tx][ty] != '#' && !vis[tx][ty])
            {
                if(mize[tx][ty] == 'E') return cur.d+1;
                q.push(Point(tx,ty, cur.d+1));
                vis[tx][ty] = true;
            }
        }
    }
    return 0;
}

int main()
{
    //freopen("in.txt","r",stdin);

    int T;
    scanf("%d", &T);
    while(T--){
        memset(vis, false, sizeof(vis));
        scanf("%d%d", &m,&n);
        for(int i = 0; i < n;i++)
        {
            scanf("%s", mize[i]);
            for(int j = 0; j < m; j++)
                if(mize[i][j] == 'S') sx = i, sy = j;
        }
        int f = 0;
        for(; f < 4; f++)
        {
            int fx = sx + mov[f][0], fy = sy + mov[f][1];
            if(INRANGE(fx,fy) && mize[fx][fy] == '.' || mize[fx][fy] == 'E')
                break;
        }

        printf("%d %d %d\n", dfs(sx, sy, f, 3), dfs(sx, sy, f, 1), bfs(sx,sy));
    }
    return 0;
}