CSES - Shared codeLink to this code: https://cses.fi/paste/334b643029ccb4c760f0d2/
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define IOS ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>order_set;
typedef pair<int, int>pr;
#define all(i) i.begin() , i.end()
#define ft first
#define sn second
#define pb push_back
#define totalone(mask) __builtin_popcount(mask)
#define chkbit(mask,bit) (mask&(1LL << bit))
#define setbit(mask,bit) (mask|(1LL << bit))
#define cngbit(mask,bit) (mask^(1LL << bit))
#define en "\n"
#define dbg(x) cerr<<#x<<" is : "<<x<<en;
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define report cout<<-1<<en
#define sum(n) ((1LL*(n)*(n+1))/ 2LL)
#define sqr(n) (1LL*(n)*(n))
#define vag(a,b) ((a + b - 1)/b)
#define coutv(v) for(auto i: v) cout<<i<<" ";cout<<en;
#define cinv(v) for(auto &i: v) cin >> i;
const int MAXN = 200005;
#define inf 1e6+5
const int mod = 1e9 + 7;
ll n;
ll a[MAXN];
struct segment_tree
{
struct node {
ll suru , ses, sm, pre, an;
void init(ll l, ll r) {
suru = l, ses = r;
if (l == r) {
sm = a[l];
pre = max(0LL, a[l]);
an = max(0LL, a[l]);
}
}
} g[4 * MAXN], ans;
void fill_cn(node &cn, node &ln, node &rn) // fill_current_node
{
cn.sm = ln.sm + rn.sm;
cn.pre = max({ln.pre, ln.sm + rn.pre});
cn.an = max({ln.an, cn.pre});
}
void build(ll cn, ll l, ll r)
{
g[cn].init(l, r);
if (l == r ) return;
ll md = l + (r - l) / 2;
build(cn * 2, l, md);
build(cn * 2 + 1, md + 1, r);
fill_cn (g[cn], g[cn * 2] , g[cn * 2 + 1]);
}
void update(ll cn, ll pos, ll val)
{
ll x = g[cn].suru;
ll y = g[cn].ses;
if (y < pos || x > pos) return;
if (pos <= x && pos >= y ) {
g[cn].sm = val;
g[cn].pre = g[cn].an = max(0LL, val);
return;
}
update(cn * 2, pos, val);
update(cn * 2 + 1, pos, val);
fill_cn(g[cn], g[cn * 2], g[cn * 2 + 1]);
}
node node_maker()
{
node nd;
nd.pre = nd.an = nd.sm = 0;
return nd;
}
node merge(node ln, node rn)
{
node cn;
cn.sm = ln.sm + rn.sm;
cn.pre = max({ln.pre, ln.sm + rn.pre});
cn.an = max({ln.an, cn.pre});
return cn;
}
node query(ll cn, ll l, ll r)
{
ll x = g[cn].suru;
ll y = g[cn].ses;
if (y < l || x > r) return node_maker();
if (l <= x && r >= y ) return g[cn];
node nd1 = query(cn * 2, l, r);
node nd2 = query(cn * 2 + 1, l, r);
return merge(nd1, nd2);
}
} stre;
void solve()
{
ll q;
cin >> n >> q;
for (ll i = 1; i <= n; i++) cin >> a[i];
stre.build(1, 1, n);
while (q--)
{
ll t, x, y;
cin >> t >> x >> y;
if (t == 2)
{
stre.ans = stre.query(1, x, y);
cout << stre.ans.an << en;
}
else {
stre.update(1, x, y);
}
}
}
int main()
{
IOS;
ll t;
t = 1;
// cin >> t;
int c = 0;
while ( t-- )
{
// cout<<"Case "<<++c<<": ";
solve();
}
return 0;
}