#428 · #2583 · Kth Largest Sum in a Binary Tree(二叉树中的第 K 大层和)

You are given the root of a binary tree and a positive integer k. Return the k-th largest level sum (the sum of node values at each level), or -1 if there are fewer than k levels. Constraints: the number of nodes is in [1, 10^5], 1 <= Node.val <= 10^6, 1 <= k <= 10^5.