poj 3009Curling 2.0

/*2014-5-821:34DFSpoj 3008*/#include <cstdio>#include <string.h>#define MAXN 30using namespace std;//inputint w,h;   //wight  hightint graph[MAXN][MAXN];int sx,sy,ex,ey;int dx[4] = {0,0,-1,1},dy[4] = {-1,1,0,0};int ans,cnt;void    dfs(int x,int y,int cnt){    int nx,ny,i;    if(cnt > ans)        return ;    for(i = 0;i < 4; i++){        nx = x+dx[i];        ny = y+dy[i];        if(nx>=h || nx<0 || ny>=w || ny<0 || graph[nx][ny]==1)//越界或立即有阻挡物剪枝            continue;        while(nx <= h && nx>=0 && ny>=0 && ny<=w && graph[nx][ny]!=1){            if(nx == ex&&ny == ey){                if(cnt+1 < ans)                    ans = cnt+1;                break;            }            nx += dx[i];            ny += dy[i];        }        if(nx==ex && ny==ey)//若由于到终点跳出去            continue;        if(nx<h && nx>=0 && ny < w && ny>=0)        {            graph[nx][ny]=0;//若是碰到阻挡物。阻挡物消失。            dfs(nx-dx[i],ny-dy[i],cnt+1);//继续搜索            graph[nx][ny]=1;//还原阻挡物。回溯        }    }}int main(){    while(scanf("%d%d",&w,&h) && w && h){        ans = 12;        for(int i = 0;i < h;i++){            for(int j = 0;j < w; j++){                scanf("%d",&graph[i][j]);                if(graph[i][j] == 2){                    sx = i,sy = j;                }                if(graph[i][j] == 3)                    ex=i,ey=j;            }        }        dfs(sx,sy,0);        if(ans <= 10)            printf("%d\n",ans);        else            printf("-1\n");    }    return 0;}