// 958. Check Completeness of a Binary Tree #include "leetcode.h" /* * given 'root' of binary tree, determine if it is a complete binary tree. in a * completely filled binary tree, every level, except possibly the last, is * completely filled, and all nodes in the last level are as far left as * possible. it can have between 1 and 2^h nodes inclusive at the last level h. */ class Solution { public: bool isCompleteTree(TreeNode *root) { vector bfs; bfs.push_back(root); int i = 0; while (i < bfs.size() && bfs[i]) { bfs.push_back(bfs[i]->left); bfs.push_back(bfs[i]->right); i++; } while (i < bfs.size() && !bfs[i]) i++; return i == bfs.size(); } };