平衡树，AC但疑惑

参考的代码

原先没在我的代码中加“org”这个变量（也就是参考的代码中的“val”），结果加上就能过，有大佬能解释一下吗

#include <bits/stdc++.h>
using namespace std;
// #include <bits/extc++.h>
// using namespace __gnu_pbds;
// tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> rbt;

using ll = long long;
const int R = 1e5 + 10;
struct Node
{
    int l, r, size, tag;
    ll val, key, org;
} tree[R];
int tot, root;
mt19937 rd;
int crt(ll val)
{
    tree[++tot].size = 1;
    tree[tot].key = rd();
    tree[tot].val = tree[tot].org = val; //在这里用到
    return tot;
}
void pushdown(int k)
{
    if (tree[k].tag != LLONG_MIN)
    {
        tree[k].val += ll(tree[k].tag) * ll(tree[k].size);
        tree[k].org += tree[k].tag; //这里用到
        if (tree[k].l)
            tree[tree[k].l].tag += tree[k].tag;
        if (tree[k].r)
            tree[tree[k].r].tag += tree[k].tag;
        tree[k].tag = 0;
    }
}
void pushup(int k)
{
    pushdown(tree[k].l);
    pushdown(tree[k].r);
    tree[k].size = tree[tree[k].l].size + tree[tree[k].r].size + 1;
    tree[k].val = tree[tree[k].l].val + tree[tree[k].r].val + tree[k].org; //这里用到，也就以上这3处了
}
void split(int k, int sz, int &x, int &y)
{
    if (k == 0)
    {
        x = y = 0;
        return;
    }
    pushdown(k);
    if (tree[tree[k].l].size + 1 <= sz)
    {
        x = k;
        split(tree[k].r, sz - (tree[tree[k].l].size + 1), tree[k].r, y);
    }
    else
    {
        y = k;
        split(tree[k].l, sz, x, tree[k].l);
    }
    pushup(k);
}
int merge(int x, int y)
{
    if (x == 0 || y == 0)
        return x + y;
    if (tree[x].key < tree[y].key)
    {
        pushdown(x);
        tree[x].r = merge(tree[x].r, y);
        pushup(x);
        return x;
    }
    else
    {
        pushdown(y);
        tree[y].l = merge(x, tree[y].l);
        pushup(y);
        return y;
    }
}
void update(int l, int r, int val)
{
    int x, y, z;
    split(root, l - 1, x, y);
    split(y, r - l + 1, y, z);
    tree[y].tag += val;
    root = merge(merge(x, y), z);
}
ll query(int l, int r)
{
    int x, y, z;
    split(root, l - 1, x, y);
    split(y, r - l + 1, y, z);
    pushdown(y);
    ll res = tree[y].val;
    root = merge(merge(x, y), z);
    return res;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n, m, x, y, k;
    char t;
    cin >> n >> m;
    int j;
    for (j = 1; j <= n; ++j)
    {
        cin >> x;
        root = merge(root, crt(x));
    }
    for (j = 1; j <= m; ++j)
    {
        cin >> t;
        if (t == '1')
        {
            cin >> x >> y >> k;
            update(x, y, k);
        }
        else
        {
            cin >> x >> y;
            cout << query(x, y) << '\n';
        }
    }
    return 0;
}