Segment Tree with Lazy Propagation

#include<bits/stdc++.h>
using namespace std;
const int N = 5e4;
struct T
{
    long long lazy, val;
};
T Tree[4*N+1];
int n, m, q;
void down(int id)
{
    long long up = Tree[id].lazy;
    Tree[id*2].lazy += up;
    Tree[id*2].val += up;

    Tree[id*2 + 1].lazy += up;
    Tree[id*2 + 1].val += up;

    Tree[id].lazy = 0;
}
long long GetMax(int id, int TreeL, int TreeR, int l, int r)
{
    if (l > r)
    {
        return 0;
    }
    if (l == TreeL && r == TreeR)
    {
        return Tree[id].val;
    }
    down(id);
    int mid = (TreeL + TreeR)/2;
    return max(GetMax(id * 2, TreeL, mid, l, min(mid, r)), GetMax(id * 2 + 1, mid + 1, TreeR, max(l, mid + 1), r));
}
void Update(int id, int TreeL, int TreeR, int l, int r, long long add)
{
    if (l > r)
    {
        return ;
    }
    if (l == TreeL && r == TreeR)
    {
        Tree[id].lazy += add;
        Tree[id].val += add;
        return ;
    }
    down(id);
    int mid = (TreeL + TreeR)/2;
    Update(id * 2, TreeL, mid, l, min(mid, r), add);
    Update(id * 2 + 1, mid + 1, TreeR, max(l, mid + 1), r, add);
    Tree[id].val = max(Tree[id*2].val, Tree[id*2 + 1].val);
}
void read()
{
   cin >> n >> m;
   int l, r, k;
   for (int i = 1; i <= m; ++ i)
   {
       cin >> l >> r >> k;
       Update(1, 1, n, l, r, k);
   }
}
void solve()
{
   int l, r;
   cin >> q;
   while (q--)
   {
       cin >> l >> r;
       cout << GetMax(1, 1, n, l, r) << '\n';
   }
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    read();
    solve();
}