20tps求助

#include <bits/stdc++.h>

using namespace std;

struct tree
{
    int l, r, value, lazy, s1, s2, flag;

    tree()
    {
        lazy = -1;
        value = 0;
        s1 = s2 = 0;
    }
};

int n, q, arr[1000005];
tree t[1000005];

void lazy1(int pos, int x)
{
    t[pos].lazy = x;
    t[pos].value = x;
    t[pos].flag = 1;

    return;
}

void lazy2(int pos, int x)
{
    t[pos].lazy = x;
    t[pos].value += x;
    t[pos].flag = 2;

    return;
}

void pushdown(int pos)
{
    if (t[pos].flag == 1)
    {
        lazy1(t[pos].s1, t[pos].lazy);
        lazy1(t[pos].s2, t[pos].lazy);
    }
    else
    {
        lazy2(t[pos].s1, t[pos].lazy);
        lazy2(t[pos].s2, t[pos].lazy);
    }

    t[pos].lazy = -1;

    return;
}

int build(int pos, int l, int r)
{
    t[pos].l = l;
    t[pos].r = r;

    if (l == r)
    {
        t[pos].value = arr[l];

        return t[pos].value;
    }

    t[pos].s1 = pos * 2;
    t[pos].s2 = pos * 2 + 1;
    t[pos].value = max(build(t[pos].s1, l, (l + r) / 2), build(t[pos].s2, (l + r) / 2 + 1, r));

    return t[pos].value;
}

int update(int pos, int l, int r, int x, int f)
{
    if (t[pos].lazy != -1)
        pushdown(pos);

    if (l <= t[pos].l && r >= t[pos].r)
    {
        if (f == 1)
            lazy1(pos, x);
        else
            lazy2(pos, x);

        return t[pos].value;
    }

    int mid = (t[pos].l + t[pos].r) / 2;

    if (l <= mid || r <= mid)
        update(t[pos].s1, l, r, x, f);

    if (l > mid || r > mid)
        update(t[pos].s2, l, r, x, f);

    t[pos].value = max(t[t[pos].s1].value, t[t[pos].s2].value);

    return t[pos].value;
}

int query(int pos, int l, int r)
{
    if (t[pos].lazy != -1)
        pushdown(pos);

    if (l <= t[pos].l && r >= t[pos].r)
        return t[pos].value;

    int mid = (t[pos].l + t[pos].r) / 2, maxx = -0x7ffffff;

    if (l <= mid || r <= mid)
        maxx = max(maxx, query(t[pos].s1, l, r));

    if (l >= mid || r > mid)
        maxx = max(maxx, query(t[pos].s2, l, r));

    t[pos].value = max(t[t[pos].s1].value, t[t[pos].s2].value);

    return maxx;
}

int main()
{
    int i;

    cin >> n >> q;

    for (i = 1; i <= n; i++)
        cin >> arr[i];

    build(1, 1, n);

    for (i = 1; i <= q; i++)
    {
        int op, l, r, x;

        cin >> op;

        if (op != 3)
        {
            cin >> l >> r >> x;

            update(1, l, r, x, op);
        }
        else
        {
            cin >> l >> r;

            cout << query(1, l, r) << endl;
        }
    }

    return 0;
}