hdu 4771 Stealing Harry Potter's Precious (BFS+状压)

struct node{
    int x,s;
    node(int _x,int _s){
        x=_x, s=_s;
    }
};

int n,m,k,sx,sy;
char graph[105][105];
int px[5],py[5];
int dp[105][105][35];

int bfs(){
    queue<node> q;
    mem(dp,-1);
    int s=0;
    rep(i,1,k) if(px[i]==sx&&py[i]==sy) s=(1<<(i-1));
    dp[sx][sy][s]=0;
    q.push(node(sx*1000+sy,s));
    if(s==((1<<k)-1))
        return dp[sx][sy][s];
    while(!q.empty()){
        node f=q.front();  q.pop();
        rep(i,0,3){
            int nx=f.x/1000+uu[i], ny=f.x%1000+vv[i];
            int s=f.s;
            if(nx<0||ny<0||nx>=n||ny>=m) continue;
            if(graph[nx][ny]==‘#‘) continue;
            rep(j,1,k) if(nx==px[j]&&ny==py[j]){
                s|=(1<<(j-1));
            }
            if(dp[nx][ny][s]!=-1) continue;
            dp[nx][ny][s]=dp[f.x/1000][f.x%1000][f.s]+1;
            q.push(node(nx*1000+ny,s));
            if(s==((1<<k)-1))
                return dp[nx][ny][s];
        }
    }
    return -1;
}

int main(){
    //freopen("test.in","r", stdin);
    while(scanf("%d%d",&n,&m),n||m){
        rep(i,0,n-1){
            scanf("%s",graph[i]);
            rep(j,0,m-1) if(graph[i][j]==‘@‘){
                sx=i, sy=j;
            }
        }
        scanf("%d",&k);
        rep(i,1,k) { scanf("%d%d",&px[i],&py[i]); --px[i], --py[i]; }
        printf("%d\n",bfs());
    }
    //fclose(stdin);
}