[洛谷] P1126 机器人搬重物(BFS搜图好题)

题目链接

/* 洛谷P1126 机器人搬重物 Apare_xzc 2019.12.8 编程语言 代码长度 用时 内存 C++ 3.82KB 34ms 784.00KB */
#include <bits/stdc++.h>
using namespace std;
int maze[100][100],sx,sy,ex,ey,m,n,sdir;
bool vis[100][100][4];
char ddd[3];
struct Node{ //结构体用于存储bfs时队列中存储的状态(坐标,方向,时间) 
	int x,y,step,dir;//横坐标，总坐标，用时，方向 
	Node(int _x=0,int _y=0,int _step=0,int _dir=0):x(_x),y(_y),step(_step),dir(_dir){}
}node;
bool ok(int x,int y,int dir);//可以走 
bool out(int x,int y);//出界了 
pair<int,int> move(int x,int y,int dir,int len);//返回停下的位置 
bool checkCreep(int xx,int yy,int dir,int &nx,int &ny);//走一步
bool checkWalk(int xx,int yy,int dir,int& nx,int& ny); //走两步
bool checkRun(int xx,int yy,int dir,int& nx,int &ny); //走三步 
inline int toRight(int dir){return (dir+1)%4;} //右转 
inline int toLeft(int dir){return (dir+3)%4;}  //左转 
void bfs();
 
int main()
{
	int ca = 0;
	while(cin>>n>>m)
	{
		if(ca++) memset(vis,0,sizeof(vis));
		for(int i=1; i<=n; ++i)
			for(int j=1;j<=m;++j)
				scanf("%d",&maze[i][j]);
		scanf("%d%d%d%d%s",&sx,&sy,&ex,&ey,ddd);
		char sss[] = "ESWN666";
		for(int i=0;i<4;++i) //确定开始的方向 ESWN对应0123 
			if(sss[i]==ddd[0]) sdir = i;
		bfs();
	}
	
	return 0;
}
bool ok(int x,int y,int dir)
{
	return (x>0&&x<=n&&y>0&&y<=m&&!vis[x][y][dir]&&maze[x][y]==0);
}
bool out(int x,int y)
{
	return (x<=0||x>n||y<=0||y>m);
} 
pair<int,int> move(int x,int y,int dir,int len)
{
	switch (dir)
	{
		case 0: return make_pair(x,y+len);
		case 1: return make_pair(x+len,y);
		case 2: return make_pair(x,y-len);
		case 3: return make_pair(x-len,y);	
	}
	return make_pair(0,0);
}

bool checkCreep(int xx,int yy,int dir,int &nx,int &ny)
{
	pair<int,int> pr = move(xx,yy,dir,1);
	int x = pr.first, y = pr.second;
	nx = x, ny = y;
	if(out(x,y)||out(x+1,y)||out(x,y+1)||out(x+1,y+1)) return false;  
	if(maze[x][y]||maze[x+1][y]||maze[x][y+1]||maze[x+1][y+1]) return false;
	return !vis[x][y][dir];
}
bool checkWalk(int xx,int yy,int dir,int& nx,int& ny)
{
	pair<int,int> pr = move(xx,yy,dir,1);
	int x = pr.first, y = pr.second;
	if(out(x,y)||out(x+1,y)||out(x,y+1)||out(x+1,y+1)) return false;  
	if(maze[x][y]||maze[x+1][y]||maze[x][y+1]||maze[x+1][y+1]) return false;
	pr = move(xx,yy,dir,2);
	x = pr.first, y = pr.second;
	if(out(x,y)||out(x+1,y)||out(x,y+1)||out(x+1,y+1)) return false;  
	if(maze[x][y]||maze[x+1][y]||maze[x][y+1]||maze[x+1][y+1]) return false;
	nx = x, ny = y;
	return !vis[x][y][dir];
}
bool checkRun(int xx,int yy,int dir,int& nx,int &ny)
{
	pair<int,int> pr = move(xx,yy,dir,1);
	int x = pr.first, y = pr.second;
	if(out(x,y)||out(x+1,y)||out(x,y+1)||out(x+1,y+1)) return false;  
	if(maze[x][y]||maze[x+1][y]||maze[x][y+1]||maze[x+1][y+1]) return false;
	pr = move(xx,yy,dir,2);
	x = pr.first, y = pr.second;
	if(out(x,y)||out(x+1,y)||out(x,y+1)||out(x+1,y+1)) return false;  
	if(maze[x][y]||maze[x+1][y]||maze[x][y+1]||maze[x+1][y+1]) return false;
	pr = move(xx,yy,dir,3);
	x = pr.first, y = pr.second;
	if(out(x,y)||out(x+1,y)||out(x,y+1)||out(x+1,y+1)) return false;  
	if(maze[x][y]||maze[x+1][y]||maze[x][y+1]||maze[x+1][y+1]) return false;
	nx = x, ny = y;
	return !vis[x][y][dir];
}
void bfs()
{
	queue<Node> Q;
	Q.push(Node(sx,sy,0,sdir));
	vis[sx][sy][sdir] = true;
	int ans = -1;
	while(!Q.empty())
	{
		node = Q.front();
		Q.pop();
		int x = node.x, y = node.y;
		int step = node.step, dir = node.dir;
		if(x==ex&&y==ey)
		{
			ans = step;
			break;
		}
		int nx=0,ny=0;
		if(checkRun(x,y,dir,nx,ny))
		{
			vis[nx][ny][dir] = true;
			Q.push(Node(nx,ny,step+1,dir));
		}
		if(checkWalk(x,y,dir,nx,ny))
		{
			vis[nx][ny][dir] = true;
			Q.push(Node(nx,ny,step+1,dir));
		}
		if(checkCreep(x,y,dir,nx,ny))
		{
			vis[nx][ny][dir] = true;
			Q.push(Node(nx,ny,step+1,dir));
		}
		if(!vis[x][y][toLeft(dir)])
		{
			vis[x][y][toLeft(dir)] = true;
			Q.push(Node(x,y,step+1,toLeft(dir)));	
		}	
		if(!vis[x][y][toRight(dir)])
		{
			vis[x][y][toRight(dir)] = true;
			Q.push(Node(x,y,step+1,toRight(dir)));
		}
	}
	printf("%d\n",ans);
}