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;
}