Shared code

// Radhe Radhe
 
#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define dl long double
#define pi pair<int, int>
#define pl pair<ll, ll> 
#define vi vector<int>
#define vc vector<char>
#define vb vector<bool>
#define vs vector<string>
#define vl vector<ll>
#define vpi vector<pi>
#define vpl vector<pl>
 
#define ff first
#define ss second
#define nline "\n"
#define no cout<<"NO"<<endl
#define yes cout<<"YES"<<endl
#define here cout<<"here"<<endl
#define all(a) a.begin(),a.end()
#define allv(a) a.rbegin(),a.rend()
#define sortAll(a) sort(all(a))
#define revAll(a) reverse(all(a))
 
#define sumAll(a) accumulate(all(a),  0LL)
#define rep(i,a,b) for(ll i=(a);i<(b);++i)
#define repv(i,a,b) for(ll i=(a);i>=(b);--i)
 
void fastio() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}
 
template<typename T>
void inp(vector<T>& arr) {
    for (auto& a : arr) cin >> a;
}
 
template<typename T>
void print(const vector<T>& arr) {
    for (const auto& val : arr) {
        cout << val << " ";
    }
    cout << "\n";
}
 
vector<int> sieve(int n) {
    vector<int> isPrime(n + 1, 1);
    isPrime[0] = isPrime[1] = 0;
    for (int i = 2; i * i <= n; i++) {
        if (isPrime[i]) {
            for (int j = i * i; j <= n; j += i) {
                isPrime[j] = 0;
            }
        }
    }
    return isPrime;
}
 
const ll M = 1e9 + 7;
 
bool even(ll a) { return (a % 2) == 0; }
bool odd(ll a) { return a & 1; }
ll mod(ll x) { return ((x % M + M) + M); }
ll add(ll a, ll b) { return mod(mod(a)+mod(b)); }
ll mul(ll a, ll b) { return mod(mod(a)*mod(b)); }
 
ll power(ll x, ll y) {
    if (y == 0) return 1;
    ll p = power(x, y / 2);
    if (y & 1) return (((p * p) % M) * x) % M;
    return (p * p) % M;
}
 
ll mod_inverse(ll a, ll m) {
    return a <= 1 ? a : 
    m-(ll)(m / a) * mod_inverse(m % a, m) % m;
}
#define debug(x) cerr << #x << " = " << (x) << endl;
 
/* -------------------------------------- */
 
class FenwickTree {
public:
    vector<ll> fen; ll n; 
    FenwickTree(ll size) {
        n = size;
        fen.assign(n+1,0);;
    }
    void build(vector<ll>& arr) {
        for (ll i = 0; i < n; i++) {
            update(i + 1, arr[i]);
        }
    }
    void update(ll idx, ll val) {
        while (idx <= n) {
            fen[idx] += val;
            idx = idx+(idx&(-idx)); 
        }
    }
    ll sum(ll idx) {
        ll res = 0;
        while (idx > 0) {
            res += fen[idx];
            idx = idx-(idx&(-idx)); 
        }return res;
    }
    ll rangeSum(ll left,ll right) {
        return sum(right) - sum(left - 1);
    }
};
 
void solve(){
    ll n,q;
    cin>>n>>q;
    vl a(n);inp(a);
 
    FenwickTree ft(n);
    ft.build(a);
 
    rep(i,0,q){
        ll qr,idx,val;
        cin>>qr>>idx>>val;
        if(qr==1){
            ft.update(idx, (ll)(val-a[idx-1]));
            a[idx-1] = val;
        }
        if(qr==2){
            cout<<ft.rangeSum(idx,val)<<nline;
        }
    }
}
 
signed main() {
    fastio();
    int t = 1;
    // cin>>t;
    while (t--) {
        solve();
    }
    return 0;
}