洛谷P3374【模板】树状数组 1(单点更新＋区间求和)

#include <iostream>
#include <cstring>
#include <cstdio>
#define mem(a,b) memset(a,b,sizeof(a));
using namespace std;
typedef long long ll;
const int maxn = 500005;
const ll INF = 0x3f3f3f3f;
int n,m;
ll a[maxn];
ll lowbit(ll t) {//取出t的最低位１
    return t&(-t);
}
ll getsum(ll x) {
    ll ans = 0;
    for(int i = x; i > 0; i -= lowbit(i)) {
        ans += a[i];
    }
    return ans;
}
void update(ll x,ll v) {
    for(int i = x; i <= n; i+=lowbit(i)) {
        a[i] += v;
    }
}
int main()
{

    cin >> n >> m;
    ll c;
    for(int i = 1; i <= n; i++) {
        cin >> c;
        update(i,c);
    }
    int op;
    ll x,y,z;
    for(int i = 1; i <= m; i++) {
        cin >> op;
        if(op == 1) {
            cin >> x >> z;
            update(x,z);
        }
        else {
            cin >> x >> y;
            cout << getsum(y) - getsum(x-1) << endl;
        }
    }
    return 0;
}