pku 2425 A Chess Game （SG）

int sg[1005];
vector<int> graph[1005];

int dfs(int x){ // position x
    if(sg[x]!=-1)
        return sg[x];
    int L=graph[x].size();
    if(L==0)
        return sg[x]=0;
    bool vis[1005] = {0};
    rep(i,0,L-1){
        vis[dfs(graph[x][i])] = true;
    }
    for(int i=0;;++i){
        if(!vis[i])
            return sg[x]=i;
    }
}

int n,Xi,a,m,pos;
int main(){
    while(scanf("%d",&n)!=EOF){
        rep(i,0,n-1) graph[i].clear();
        rep(i,0,n-1){
            scanf("%d",&Xi);
            while(Xi--){
                scanf("%d",&a);
                graph[i].push_back(a);
            }
        }
        mem(sg,-1);

        while(scanf("%d",&m),m){
            int ans=0;
            rep(i,1,m){
                scanf("%d",&pos);
                ans=ans^dfs(pos);
            }
            if(!ans)
                puts("LOSE");
            else
                puts("WIN");
        }
    }
}