MST 小希的迷宫

不知道有没有更好的做法（省空间，省时间）。

http://acm.hdu.edu.cn/webcontest/contest_showproblem.php?pid=1002&ojid=0&cid=1304&hide=0

# include <cstdio>
# include <cstring>

# define N 100000 + 5

int p[N];
bool ok, vis[N];

void init(void)
{
    ok = false;
    for (int i = 1; i < N; ++i) p[i] = i;
    memset(vis, false, sizeof(vis));
}

int find(int x) {return x==p[x] ? x:(p[x]=find(p[x]));}

int main()
{
    int x, y;

    init();
    while (~scanf("%d%d", &x, &y))
    {
        if (x==-1 && y==-1) break;
        if (x==0 && y==0)
        {
            if (ok == false)
            {
                int fa = -1;
                for (int i = 1; i < N; ++i) if (vis[i])
                {
                    if (fa == -1) fa = find(i);
                    else if (fa != find(i)) {ok = true;break;}
                }
            }
            puts(ok ? "No":"Yes");
            init();
        }
        else if(ok == false)
        {
            x = find(x), y = find(y);
            vis[x] = true, vis[y] = true;
            if (x != y) p[y] = x;
            else ok = true;
        }
    }

    return 0;
}