Shared code

#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;
}