Root Equals Average of All Subtrees

Problem: Check Whether the Root Equals the Average of Every Subtree (Variant) You are given a binary tree root where each node stores an integer value. For any node x in the tree, define its subtree as the set of nodes consisting of x and all its descendants. Define the average of that subtree as the arithmetic mean of all node values inside the subtree. Determine whether root.val equals the average of the subtree of every node in the tree. Return true if for every node x, avg(subtree(x)) == root.val. Otherwise return false. Input A binary tree root. Node values are in [-10^9, 10^9]. Number of nodes n: 1 <= n <= 2 * 10^5. Output A boolean true/false. Notes Treat the average as an exact rational number: compare sum(subtree) / size(subtree) to root.val exactly (avoid floating-point tolerance issues). Sample Tests Input: [5,5,5] Output: true Input: [4,8,5,0,1,null,6] Output: false Input: [1] Output: true Input: [2,1,3] Output: false Input: [0,0,0,0,null,null,0] Output: true Example Input [5,5,5] Output true