学习模板（线段树）

#include<iostream>
#include<algorithm>
#include<queue>
#include<stack>
#include<cstring>
#include<cstdio>
#include<cmath>
using namespace std;
int n,m,a[500005],ans;
struct node
{
    int left,right;
    int sum;
}tree[2000020];//4*500000内存大小
void build(int left,int right,int index)
{
    tree[index].left=left;
    tree[index].right=right;
    if(left==right)return;
    int mid=(left+right)/2;
    build(left,mid,2*index);
    build(mid+1,right,2*index+1);
}
int input(int index)//维护
{
    if(tree[index].left==tree[index].right)
    {
        return tree[index].sum=a[tree[index].left];
    }
     tree[index].sum=input(2*index)+input(2*index+1);
    return  tree[index].sum;
}
void search(int index,int l,int r)
{
    if(tree[index].left>=l&&tree[index].right<=r)
    {
       ans+=tree[index].sum;
       return ;
    }
    if(tree[2*index].right>=l)search(2*index,l,r);
    if(tree[2*index+1].left<=r)search(2*index+1,l,r);
}
void correct(int index,int dis,int k)
{
    tree[index].sum+=k;
    if(tree[index].left==tree[index].right)return ;
    if(dis<=tree[2*index].right)
        correct(2*index,dis,k);
      if(dis>=tree[2*index+1].left)
        correct(2*index+1,dis,k);
} 
int main()
{
    ios::sync_with_stdio(false);
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    build(1,n,1);
    input(1);
    for(int i=1;i<=m;i++)
    {
        int a,b,c;
        cin>>a>>b>>c;
        if(a==1)
        {
            correct(1,b,c);
        }
        if(a==2)
        {
            ans=0;
           search(1,b,c);
           printf("%dn",ans);
        }
    }
}