Grant Access (permissions propagation / access control)

Implement the core logic of a “Grant Access” permission system on a hierarchical resource tree (e.g., Org -> Project -> Folder -> Document). You can grant or revoke a permission (e.g., READ) for a user at any node. The rule applies to the node and all its descendants, unless a more specific rule is applied deeper in the tree. Later operations override earlier ones. Design a data structure supporting: grant(user, node) revoke(user, node) check(user, node) -> bool Constraints: Up to N = 2*10^5 nodes and Q = 2*10^5 operations. Must handle multiple grants/revokes with overriding semantics. Define a clear input format and output true/false for each check.