1180 bfs

一道典型的 bfs。这个题的“天梯”有点坑。在判断，讨论天梯的方向的时候有点麻烦

跪了两次：

1. 在经过天梯后，依然需要check一次。。。

2. 原地不动的时候，我居然直接把now修改了，跪了一次。。。

#pragma warning(disable:4996)
#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
using namespace std;

int m, n;
int sx, sy;
char mapp[25][25];
int vis[25][25];
int mx[4] = { -1, 0, 1, 0 };
int my[4] = { 0, 1, 0, -1 };
int ans;

struct Node
{
	int x, y;
	int time;
	Node(int a, int b, int c)
	{
		x = a; y = b; time = c;
	}
	friend bool operator<(const Node &a, const Node &b)
	{
		return a.time>b.time;
	}
};

bool check(Node & a)
{
	int x = a.x;
	int y = a.y;
	if (x<1 || x>m || y<1 || y>n || mapp[x][y] == '*' || vis[x][y] == 1)
		return 0;

	return 1;
}

void bfs()
{
	Node now(sx, sy, 0);
	vis[sx][sy] = 1;
	priority_queue<Node> q;
	q.push(now);

	while (!q.empty())
	{
		now = q.top();
		q.pop();
		if (mapp[now.x][now.y] == 'T')
		{
			ans = now.time;
			return;
		}

		for (int i = 0; i < 4; ++i)
		{
			Node next(now.x + mx[i], now.y + my[i], now.time + 1);
			if (check(next))
			{
				if (mapp[next.x][next.y] == '.' || mapp[next.x][next.y] == 'T')
				{
					q.push(next);
					vis[next.x][next.y] = 1;
				}

				else if (mapp[next.x][next.y] == '|')
				{
					if (next.time % 2 == 0 && i % 2 == 1)  //横向移动
					{
						next.y += my[i];
						if (check(next))
						{
							q.push(next);
							vis[next.x][next.y] = 1;
						}
					}
					else if (next.time % 2 == 1 && i % 2 == 0)  //竖向移动
					{
						next.x += mx[i];
						if (check(next))
						{
							q.push(next);
							vis[next.x][next.y] = 1;
						}
					}
					else   //原地不动
					{
						Node next2(now.x, now.y, now.time + 1);
						q.push(next2);
					}
				}
				else if (mapp[next.x][next.y] == '-')
				{
					if (next.time % 2 == 1 && i % 2 == 1)  //横向移动
					{
						next.y += my[i];
						if (check(next))
						{
							q.push(next);
							vis[next.x][next.y] = 1;
						}
					}
					else if (next.time % 2 == 0 && i % 2 == 0)  //竖向移动
					{
						next.x += mx[i];
						if (check(next))
						{
							q.push(next);
							vis[next.x][next.y] = 1;
						}
					}
					else    //原地不动
					{
						Node next2(now.x, now.y, now.time + 1);
						q.push(next2);
					}
				}
			}
		}
	}
}

int main()
{
	freopen("in.txt", "r", stdin);
	while (cin >> m >> n)
	{
		memset(vis, 0, sizeof(vis));
		for (int i = 1; i <= m; ++i)
		{
			for (int j = 1; j <= n; ++j)
			{
				cin >> mapp[i][j];
				if (mapp[i][j] == 'S')
				{
					sx = i; sy = j;
				}
			}
		}
		bfs();
		cout << ans << endl;
	}
	return 0;
}