百练 4116 拯救行动

4116:拯救行动

#include<iostream>
#include<cstdio>
#include<queue>
#include<vector>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=200+5;
int R,C,vis[maxn][maxn];
char G[maxn][maxn];
int r0,c0,r1,c1;
struct Point{
int x,y,step;
bool operator < (const Point& p) const {
return step>p.step;
}
Point(int x,int y,int s): x(x),y(y),step(s){}
};
bool inside(int x,int y)
{
return x>=0&&x<R&&y>=0&&y<C;
}
int bfs(int i,int j)
{
priority_queue<Point> Q;
Q.push(Point(i,j,0));
vis[i][j]=1;
while(!Q.empty())
{
int x=Q.top().x,y=Q.top().y,step=Q.top().step;Q.pop();
if(x==r1&&y==c1) return step;
for(int dx=-1;dx<=1;dx++)
for(int dy=-1;dy<=1;dy++)
{
if((dx&&dy)||(!dx&&!dy)) continue;
int nx=x+dx;
int ny=y+dy;
if(!inside(nx,ny)||G[nx][ny]=='#'||vis[nx][ny]) continue;
if(G[nx][ny]=='x') Q.push(Point(nx,ny,step+2));
else Q.push(Point(nx,ny,step+1));
vis[nx][ny]=1;
}
}
return -1;
}
int main()
{
int T;
cin>>T;
while(T--)
{
cin>>R>>C;
for(int i=0;i<R;i++)
for(int j=0;j<C;j++)
{
cin>>G[i][j];
if(G[i][j]=='a') r1=i,c1=j;
else if(G[i][j]=='r') r0=i,c0=j;
}
memset(vis,0,sizeof(vis));
int ans=bfs(r0,c0);
if(ans==-1) cout<<"Impossible"<<endl;
else cout<<ans<<endl;
}
return 0;
}