Problem - Subtree Queries

Given a tree with $n$ nodes, each with a value. Process $q$ queries:

$1.$ Update: change node $u$'s value to $v$

$2.$ Query: return the sum of values in $u$n, q \leq 2 \cdot 10^5$. You've found the perfect Euler tour problem. Subtree becomes a range. Point update on node becomes point update on tour. Subtree sum becomes range sum.s subtree

Constraints: $n, q \leq 2 \cdot 10^5$. You've found the perfect Euler tour problem. Subtree becomes a range. Point update on node becomes point update on tour. Subtree sum becomes range sum.