ZOJ 1649 Rescue（BFS）

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#include<stdio.h>
#include<string.h>
#include<string>
#include<queue>
#include<algorithm>
using namespace std;
const int maxm=205;
const int inf=1<<29;
int m,n;
int x1,y1,x2,y2;
char map[maxm][maxm];
int vis[maxm][maxm];
int w[maxm][maxm];
int dir[4][2]={{1,0},{0,1},{0,-1},{-1,0}};
struct node
{
int x;
int y;
int step;
int time;
bool operator <(const node s)const
{
return time>s.time;
}
};
void bfs()
{
struct node now,pre;
priority_queue<node>q;
pre.x=x1;
pre.y=y1;
pre.step=0;
pre.time=0;
q.push(pre);
while(!q.empty())
{
pre=q.top();
q.pop();
for(int i=0; i<4; i++)
{
now.x=pre.x+dir[i][0];
now.y=pre.y+dir[i][1];
now.step=pre.step+1;
now.time=pre.time+1;
if(now.x>=0&&now.x<m&&now.y>=0&&now.y<n&&map[now.x][now.y]!='#')
{
if(map[now.x][now.y]=='x')
{
now.time++;
}
if(w[now.x][now.y]>now.time)
{
w[now.x][now.y]=now.time;
q.push(now);
}
}
}
}
return;
}
int main()
{
while(scanf("%d%d",&m,&n)!=EOF)
{
for(int i=0; i<m; i++)
{
scanf("%s",map[i]);
for(int j=0; j<n; j++)
{
w[i][j]=inf;
if(map[i][j]=='a')
{
x1=i;
y1=j;
}
if(map[i][j]=='r')
{
x2=i;
y2=j;
}
}
}
w[x1][y1]=0;
bfs();
if(w[x2][y2]==inf)
{
printf("Poor ANGEL has to stay in the prison all his life.n");
}
else
{
printf("%dn",w[x2][y2]);
}
}
return 0;
}