Binary Tree Level Average (Level-order traversal)

Problem Given the root root of a binary tree, compute the average value of the nodes on each level using level-order traversal (BFS), and output the averages from top to bottom. If a level has k nodes, its average is the sum of values on that level divided by k. Each level’s average should be printed as a floating-point number. Input (stdin) The binary tree is provided in level-order array form, where null indicates a missing child. Line 1: a space-separated sequence representing the tree (e.g., 3 9 20 null null 15 7). Output (stdout) Print the per-level averages in one line, space-separated, from the root level to the deepest level. Constraints Number of nodes n: 0 <= n <= 1e5 Node values: -1e9 <= val <= 1e9 Target complexity: O(n) time. Examples Example 1 Input: 3 9 20 null null 15 7 Output: 3 14.5 11 Example 2 Input: 1 Output: 1 Example Input 3 9 20 null null 15 7 Output 3 14.5 11