求助，动态开点线段树要么RE要么MLE

#include <iostream>
#include <cstdio>
using namespace std;
const int N = 3e5 + 10;
const int M = N * 50;
int n, q, node_cnt = 0;
struct SGT {
    int ls[M], rs[M];
    struct node { int l, r, val, tag; } tr[M];
    inline void add_point(int &p, int l, int r) {
        p = ++node_cnt, tr[p].l = l, tr[p].r = r;
    }
    inline void pushup(int p) {
        tr[p].val = tr[ls[p]].val + tr[rs[p]].val;
    }
    inline void mk(int p, int op) {
        if (op == 0) return;
        if (op == 1) tr[p].val = tr[p].r - tr[p].l + 1, tr[p].tag = 1;
        if (op == 2) tr[p].val = 0, tr[p].tag = 2;
    }
    void pushdown(int p, int l, int r) {
        int mid = (l + r) >> 1;
        if (!ls[p]) add_point(ls[p], l, mid);
        if (!rs[p]) add_point(rs[p], mid + 1, r);
        mk(ls[p], tr[p].tag);
        mk(rs[p], tr[p].tag);
        tr[p].tag = 0;
    }
    void update(int &p, int l, int r, int ql, int qr, int op) {
        if (!p) add_point(p, l, r);
        if (ql <= l && r <= qr) return mk(p, op);
        pushdown(p, l, r);
        int mid = (l + r) >> 1;
        if (ql <= mid) update(ls[p], l, mid, ql, qr, op);
        if (qr > mid) update(rs[p], mid + 1, r, ql, qr, op);
        pushup(p);
    }
} T;
signed main() {
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    cin >> n >> q;
    int root = 0;
    for (int l, r, op; q--;) {
        cin >> l >> r >> op;
        T.update(root, 1, n, l, r, op);
        cout << n - T.tr[1].val << '\n';
    }
}