我第一次过这个题的代码是这样的：

#include <bits/stdc++.h>

using namespace std;

#define il inline
#define re register
#define rep(i, s, e) for (re int i = s; i <= e; ++i)
#define drep(i, s, e) for (re int i = s; i >= e; --i)
#define file(a) freopen(#a".in", "r", stdin), freopen(#a".out", "w", stdout)

const int N = 200000 + 10;
const int MLOG = 40;

il int read() {
    int x = 0; bool f = true; char c = getchar();
    while (!isdigit(c)) {if (c == '-') f = false; c = getchar();}
    while (isdigit(c)) x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
    return f ? x : -x;
}

int n, m, dep[N];

int tot, val[N * MLOG], lson[N * MLOG], rson[N * MLOG], rt[N];

#define ls lson[u]
#define rs rson[u]
#define mid ((l + r) >> 1)

int build(int l, int r) {
    int u = ++tot;
    if (l == r) { val[u] = l; return u; }
    ls = build(l, mid), rs = build(mid + 1, r);
    return u;
}

il int clone(int u) {
    val[++tot] = val[u], lson[tot] = ls, rson[tot] = rs;
    return tot;
}

int modify(int p, int x, int now, int l, int r) {
    int u = clone(now);
    if (l == r) { val[u] = x; return u; }
    if (p <= mid) ls = modify(p, x, ls, l, mid);
    else rs = modify(p, x, rs, mid + 1, r);
    return u;
}

int query(int p, int u, int l, int r) {
    if (l == r) return val[u];
    return (p <= mid) ? query(p, ls, l, mid) : query(p, rs, mid + 1, r);
}

int getf(int u, int ver) {
    for (int nxt = query(u, rt[ver], 1, n); u != nxt; u = nxt, nxt = query(u, rt[ver], 1, n)) ;
    return u;
}

int main() {
    n = read(), m = read(), rt[0] = build(1, n);
    rep(i, 1, n) dep[i] = 1;
    rep(i, 1, m) {
        int opt = read();
        if (opt == 1) {
            int u = getf(read(), i - 1), v = getf(read(), i - 1);
            if (dep[u] > dep[v]) swap(u, v);
            else if (dep[u] == dep[v]) ++dep[v];
            rt[i] = modify(u, v, rt[i - 1], 1, n);
        }
        else if (opt == 2) rt[i] = rt[read()];
        else {
            rt[i] = rt[i - 1];
            int u = getf(read(), i), v = getf(read(), i);
            printf("%d\n", u == v);
        }
    }
    return 0;
}

大家可以很明显地看到我代码中的 dep 没有用可持久化数组维护，相当于直接从上一次操作继承，这样显然是错的（可以先把一个点的 dep 弄到很大，再把小的弄成一条链挂在它下面然后多次查询卡掉它），但是它过了。。。

所以管理能否加强一下数据呢