U198002 你能回答这些问题吗

https://www.acwing.com/file_system/file/content/whole/index/content/5377641/

include <bits/stdc++.h>

using namespace std;

const int N = 500010;

int n, m;
int w[N];
struct node {
int l, r;
int tmax, lmax, rmax, sum;
} tr[N * 4];

void pushup(node &u, node &l, node &r) {
u.sum = l.sum + r.sum;
u.lmax = max(l.lmax, l.sum + r.lmax);
u.rmax = max(r.rmax, r.sum + l.rmax);
u.tmax = max(l.rmax + r.lmax, max(l.tmax, r.tmax));
}

void pushup(int u) {
pushup(tr[u], tr[u << 1], tr[u << 1 | 1]);
}

void build(int u, int l, int r) {
if (l == r) tr[u] = {l, r, w[r], w[r], w[r], w[r]};
else {
tr[u] = {l, r};
int mid = l + r >> 1;
build(u << 1, l, mid);
build(u << 1 | 1, mid + 1, r);
pushup(u);
}
}

void modify(int u, int x, int v) {
if (tr[u].l == x && tr[u].r == x) tr[u] = {x, x, v, v, v, v};
else {
int mid = tr[u].l + tr[u].r >> 1;
if (x <= mid) modify(u << 1, x, v);
else modify(u << 1 | 1, x, v);
pushup(u);
}
}

node query(int u, int l, int r) {
if (tr[u].l >= l && tr[u].r <= r) return tr[u];

int mid = tr[u].l + tr[u].r >> 1;
if (r <= mid) return query(u << 1, l, r);
else if (l > mid) return query(u << 1 | 1, l, r);
else {
    auto left = query(u << 1, l, r);
    auto right = query(u << 1 | 1, l, r);
    node res;
    pushup(res, left, right);
    return res;
}

}

int main() {
cin >> n >> m;
for (int i = 1; i <= n; i++) cin >> w[i];

build(1, 1, n);


int op, x, y;
while (m--) {
    cin >> op >> x >> y;
    if (op == 1) {
        if (x > y) swap(x, y);
        cout << query(1, x, y).tmax << endl;
    } else {
        modify(1, x, y);
    }
}

return 0;

}