Problem - Range Addition

Given an array of size $n$ initialized to 0, perform operations:

• add(l, r, val): Add val to all elements in range $[l, r]$
• query(l, r): Return sum of elements in range $[l, r]$ This requires lazy propagation because:

$1.$ Range updates would be $O(n)$ with point updates

$2.$ You need both range updates and range queries Implement a segment tree with lazy propagation for range add and range sum. Constraints: $n$ up to $10^5$, up to $10^5$ operations.