Splay模板写挂了 求救

如题，大部分按照oiwiki的板子写的

但是insert部分好像出了问题，求帮看看（）

十分感激

#include <iostream>
using namespace std;
int rt, tot, fa[100005], ch[100005][2];
int val[100005], cnt[100005], sz[100005];
int v[100005];
void maintain(int x) {
    sz[x] = sz[ch[x][0]] + sz[ch[x][1]] + cnt[x];
}
bool get(int x) {
    return x == ch[fa[x]][1];
}
void clear(int x) {
    ch[x][0] = ch[x][1] = fa[x] = val[x] = sz[x] = cnt[x] = 0;
}
void rotate(int x) {
    int y = fa[x], z = fa[y], chk = get(x);
    ch[y][chk] = ch[x][chk ^ 1];
    if (ch[x][chk ^ 1]) fa[ch[x][chk ^ 1]] = y;
    ch[x][chk ^ 1] = y;
    fa[y] = x;
    fa[x] = z;
    if (z) ch[z][y == ch[z][1]] = x;
    maintain(y);
    maintain(x);
}
/*void splay(int x) {
    for (int f = fa[x]; f = fa[x], f; rotate(x)) {
        if (fa[f]) rotate(get(x) == get(f) ? f : x);
    }
    rt = x;
}*/
void splay(int x, int goal){
    for (int i; (i = fa[x]) != goal; rotate(x)) {
        if (fa[i] != goal) {
            rotate(get(x) == get(i) ? i : x);
        }
    }
    if (goal == 0) {
        rt = x;
    }
}
void insert(int k) {
    if (!rt) {
        val[++tot] = k;
        cnt[tot]++;
        rt = tot;
        maintain(rt);
        return ;
    }
    int cur = rt, f = 0;
    while (1) {
        if (val[cur] == k) {
            cnt[cur]++;
            maintain(cur);
            maintain(f);
            rotate(cur);
            break;
        }
        f = cur;
        cur = ch[cur][val[cur] < k];
        if (!cur) {
            val[++tot] = k;
            cnt[tot]++;
            fa[tot] = f;
            ch[f][val[f] < k] = tot;
            maintain(tot);
            maintain(f);
            rotate(tot);
            break;
        }
    }
}
int find(int k) {
  int cur = rt;
  while (1) {
    if (ch[cur][0] && k <= sz[ch[cur][0]]) {
      cur = ch[cur][0];
    } else {
      k -= cnt[cur] + sz[ch[cur][0]];
      if (k <= 0) {
        rotate(cur);
        return val[cur];
      }
      cur = ch[cur][1];
    }
  }
}
void dfs(int rt) {
    if (v[rt]) {
        cout << rt << " ";
        return ;
    }
    v[rt] = 1;
    if (rt == 0) {
        return ;
    }
    if (ch[rt][0]) dfs(ch[rt][0]);
    if (ch[rt][1]) dfs(ch[rt][1]);
    cout << rt << " ";
}
int main() {
    int m, n;
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        insert(i);
    }
    while (m--) {
        int x, y;
        cin >> x >> y;
        splay(find(x), 0);
        splay(find(y + 2), find(x));
    }
    dfs(rt);
    return 0; 
}