http://acm.pku.edu.cn/JudgeOnline/problem?id=2312poj 2312 Battle City
简单的BFS
Source Code
Problem: 2312 |
|
User: lovecanon |
Memory: 1244K |
|
Time: 16MS |
Language: GCC |
|
Result: Accepted |
#include<stdio.h>
typedef struct node
{
int x;
int y;
}node;
node Q[100000];
char board[301][301];
int step[301][301];
int m,n;
const int dx[]={0,0,-1,1},dy[]={-1,1,0,0};
int ok(int x,int y)
{
if(x>=0&&x<m&&y>=0&&y<n) return 1;
else return 0;
}
void solve(int x1,int y1,int x2,int y2)
{
int i,j,cntx,cnty,nextx,nexty,head,tail,tmp,minstep=0x7fffffff;
cntx=x1;cnty=y1;head=tail=0;
for(i=0;i<m;i++)
for(j=0;j<n;j++)
step[i][j]=0x7fffffff;
step[cntx][cnty]=0;
while(1)
{
for(i=0;i<4;i++)
{
nextx=cntx+dx[i];
nexty=cnty+dy[i];
if(ok(nextx,nexty))
{
if(board[nextx][nexty]=='E')
{
tmp=step[cntx][cnty]+1;
if(tmp<step[nextx][nexty])
{
step[nextx][nexty]=tmp;
Q[++tail].x=nextx;
Q[tail].y=nexty;
}
}
if(board[nextx][nexty]=='B')
{
tmp=step[cntx][cnty]+2;
if(tmp<step[nextx][nexty])
{
step[nextx][nexty]=tmp;
Q[++tail].x=nextx;
Q[tail].y=nexty;
}
}
if(board[nextx][nexty]=='T')
{
if(step[cntx][cnty]+1<minstep) minstep=step[cntx][cnty]+1;
}
}
}
if(head==tail) break;
else
{
cntx=Q[++head].x;
cnty=Q[head].y;
}
}
if(minstep==0x7fffffff) printf("-1\n");
else printf("%d\n",minstep);
}
int main()
{
while(1)
{
int i,j;
int x1,y1,x2,y2;
scanf("%d%d",&m,&n);
getchar();
if(m==0&&n==0) return 0;
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
board[i][j]=getchar();
if(board[i][j]=='Y')
{
x1=i;y1=j;
}
if(board[i][j]=='T')
{
x2=i;y2=j;
}
}
getchar();
}
solve(x1,y1,x2,y2);
}
return 0;
}