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摘要： Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array. Example 1: Note: 这个题主要想总结一下bfs算法： 广度优先遍历：类 阅读全文

摘要： Given a binary tree, return the postorder traversal of its nodes' values. Example: Follow up: Recursive solution is trivial, could you do it iterative 阅读全文

摘要： Given a binary tree, return the inorder traversal of its nodes' values. Example: Follow up: Recursive solution is trivial, could you do it iteratively 阅读全文

摘要： Given a binary tree, return the preorder traversal of its nodes' values. Example: Follow up: Recursive solution is trivial, could you do it iterativel 阅读全文