hdu 1180（诡异的楼梯）

这题还真是诡异，明明思路很清晰，BFS也很熟练 的敲出来了，可就是改了半天，原来问题在这里，“Harry从来不在楼梯上停留”，这里提示的很明显了，他除了不再楼梯上停留，其他地方是可以停留的，当然，也就只有在遇到楼梯，又暂时过不去时，才有必要在原地停留，郁闷呀，疏忽了这里，wa了好几次……

hdu1180 代码

#include <iostream>
#include <queue>
using namespace std;
struct Node
{
int x, y, time;
Node(int _x=0,int _y=0,int _time=0):x(_x),y(_y),time(_time){};
};

Node first;
int dir[4][2] = {{0,1},{0,-1},{1,0},{-1,0}};
int n, m, a, b;
char map[21][21];
bool vis[21][21];
queue <Node> Q;

int bfs()
{
int fx, fy;
first.x = a;
first.y = b;
first.time = 0;
Q.push(first);
while (!Q.empty())
{
first = Q.front();
Q.pop();

if (map[first.x][first.y] == 'T')
{
return first.time;
}

int i;
for (i = 0; i < 4; ++i)
{
fx = first.x + dir[i][0];
fy = first.y + dir[i][1];

if (fx >= 0 && fx < n && fy >= 0 && fy < m && map[fx][fy] != '*' && !vis[fx][fy])
{
if (map[fx][fy] == '.' || map[fx][fy] == 'T')
{
vis[fx][fy] = 1;
Q.push(Node(fx,fy,first.time+1));
}
else if (map[fx][fy] == '-')
{
if (first.time % 2 == 0)
{
if (fx == first.x)
{
fy = 2*fy - first.y;
if (fy >= 0 && fy < m && map[fx][fy] != '*' && !vis[fx][fy])
{
vis[fx][fy] = 1;
Q.push(Node(fx,fy,first.time+1));
}
}
else
Q.push(Node(first.x,first.y,first.time+1));//遇到楼梯，但方向不对，原地停留
}
else
{
if (fy == first.y)
{
fx = 2*fx - first.x;
if (fx >= 0 && fx < n && map[fx][fy] != '*' && !vis[fx][fy])
{
vis[fx][fy] = 1;
Q.push(Node(fx,fy,first.time+1));
}
}
else
Q.push(Node(first.x,first.y,first.time+1));//同样，原地停留
}
}
else if (map[fx][fy] == '|')
{
if (first.time % 2 == 0)
{
if (fy == first.y)
{
fx = 2*fx - first.x;
if (fx >= 0 && fx < n && map[fx][fy] != '*' && !vis[fx][fy])
{
vis[fx][fy] = 1;
Q.push(Node(fx,fy,first.time+1));
}
}
else
Q.push(Node(first.x,first.y,first.time+1));
}
else
{
if (fx == first.x)
{
fy = 2*fy - first.y;
if (fy >= 0 && fy < m && map[fx][fy] != '*' && !vis[fx][fy])
{
vis[fx][fy] = 1;
Q.push(Node(fx,fy,first.time+1));
}
}
else
Q.push(Node(first.x,first.y,first.time+1));
}
}
}
}
}
return -1;
}

int main()
{
while (scanf("%d %d", &n, &m) != EOF)
{
int i, j;
for (i = 0; i < n; ++i)
{
getchar();
for (j = 0; j < m; ++j)
{
scanf("%c", &map[i][j]);
if (map[i][j] == 'S')
{
a = i;
b = j;
}
vis[i][j]=0;
}
}
vis[a][b] = 1;
while (!Q.empty())
{
Q.pop();
}
printf("%d\n",bfs());
}
return 0;
}