Lazy segment tree

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;

#define si(n) scanf("%d",&n)
#define MAX 100005

long long arr[MAX],tree[4*MAX],lazy[4*MAX];

void update(int node,int tl,int tr,int l,int r,int val){
    //
    if(lazy[node]){
        tree[node]+=(tr-tl+1)*lazy[node];

        if (tl != tr){
            lazy[node*2]+=lazy[node];
            lazy[node*2+1]+=lazy[node];
        }
        lazy[node]=0;
    }

    if(tl>tr || tl>r || tr<l){
        //cout<<"here"<<endl;
        return ;
    }
    if(tl>=l && tr<=r){
        tree[node]+=(tr-tl+1)*val;
        if(tl != tr){
            lazy[node*2]+=val;
            lazy[node*2+1]+=val;
        }
        return ;
    }
    int mid=(tl+tr)/2;
    //cout<<mid<<endl;
    update(node*2,tl,mid,l,r,val);
    update(node*2+1,mid+1,tr,l,r,val);

    tree[node]=tree[node*2]+tree[node*2+1];
}

long long  sum(int node,int tl,int tr,int l,int r){
    if(tl>tr || tl>r || tr<l)
        return 0;
    if(lazy[node]!=0){
        tree[node]+=(tr-tl+1)*lazy[node];
        if(tl != tr){
            lazy[node*2]+=lazy[node];
            lazy[node*2+1]+=lazy[node];
        }
        lazy[node]=0;
    }
    if(tl>=l && tr<=r)
        return tree[node];
    int mid=(tl+tr)/2;

    return sum(node*2,tl,mid,l,r)+
        sum(node*2+1,mid+1,tr,l,r);
}