能不能帮忙找找有没有什么微小的bug

qwq

//Binary Index Tree 23/11/04
//区间求和+单点更新
#include<bits/stdc++.h>
using namespace std;

int n,q;
int a[1000005];
int c[2000005];

int lowbit(int x){
    return x&-x;
}

int sum(int pos){
    int res=0;
    for(int i=pos;i>=1;i-=lowbit(i))
        res+=c[i];
    return res;    
}

void addnew(int pos,int val){
    for(int i=pos;i<=n;i+=lowbit(i))
        c[i]+=val;
}


int main(){
    scanf("%d %d",&n,&q);
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
        addnew(i,a[i]);
    }
    for(int i=1;i<=q;i++){
        int x,y,z;
        scanf("%d %d %d",&x,&y,&z);
        if(x==1){
            addnew(y,z);
        }else{
            printf("%d\n",(sum(z)-sum(y-1)));
        }
    }
    return 0;
}