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| #include <iostream>
#include <cstdio>
using namespace std;
const int N = 5e4 + 10;
int n, m, w[N];
struct Node
{
int l, r, mx, sum, lmx, rmx;
}tr[N << 2];
void pushup (int x)
{
tr[x].sum = tr[x << 1].sum + tr[x << 1 | 1].sum;
tr[x].lmx = max(tr[x << 1].lmx, tr[x << 1].sum + tr[x << 1 | 1].lmx);
tr[x].rmx = max(tr[x << 1 | 1].rmx, tr[x << 1].rmx + tr[x << 1 | 1].sum);
tr[x].mx = max(tr[x << 1].rmx + tr[x << 1 | 1].lmx, max(tr[x << 1].mx, tr[x << 1 | 1].mx));
}
void build (int x, int l, int r)
{
tr[x].l = l;
tr[x].r = r;
if (l == r)
{
tr[x].sum = tr[x].mx = tr[x].lmx = tr[x].rmx = w[l];
return;
}
int mid = l + r >> 1;
build(x << 1, l, mid);
build(x << 1 | 1, mid + 1, r);
pushup(x);
}
void modify (int x, int t, int k)
{
if (tr[x].l == tr[x].r)
{
tr[x].sum = tr[x].mx = tr[x].lmx = tr[x].rmx = k;
return;
}
int mid = tr[x].l + tr[x].r >> 1;
if (t <= mid)
modify(x << 1, t, k);
if (t > mid)
modify(x << 1 | 1, t, k);
pushup(x);
}
Node query (int x, int l, int r)
{
if (tr[x].l >= l && tr[x].r <= r)
return tr[x];
int mid = tr[x].l + tr[x].r >> 1;
if (l > mid)
return query(x << 1 | 1, l, r);
if (r <= mid)
return query(x << 1, l, r);
Node res, lres = query(x << 1, l, r), rres = query(x << 1 | 1, l, r);
res.sum = lres.sum + rres.sum;
res.lmx = max(lres.lmx, lres.sum + rres.lmx);
res.rmx = max(rres.rmx, rres.sum + lres.rmx);
res.mx = max(lres.rmx + rres.lmx, max(lres.mx, rres.mx));
return res;
}
int main ()
{
scanf("%d", &n);
for (int i = 1; i <= n; i++)
scanf("%d", &w[i]);
build(1, 1, n);
scanf("%d", &m);
for (int op, x, y; m; m--)
{
scanf("%d%d%d", &op, &x, &y);
if (op)
printf("%d\n", query(1, x, y).mx);
else
modify(1, x, y);
}
return 0;
}
|