Recently, I've just encountered this problem: Given a tree with
vertices and rooted at
. Each vertex has an initial value, and initially, all these values are
. There are
queries of two types: - "1 u": Find the sum of values of vertices in the subtree rooted at u. - "2 u": Find the value at vertex u. - "3 u v x": Increase the values of vertices on the simple path from u to v by x. Answer the queries of type 1 and 2. Constraints