If this pull request (PR) pertains to Chinese-to-English translation, please confirm that you have read the contribution guidelines and complete the checklist below:
[ ] This PR represents the translation of a single, complete document, or contains only bug fixes.
[ ] The translation accurately conveys the original meaning and intent of the Chinese version. If deviations exist, I have provided explanatory comments to clarify the reasons.
If this pull request (PR) is associated with coding or code transpilation, please attach the relevant console outputs to the PR and complete the following checklist:
[ ] I have thoroughly reviewed the code, focusing on its formatting, comments, indentation, and file headers.
[ ] I have confirmed that the code execution outputs are consistent with those produced by the reference code (Python or Java).
[ ] The code is designed to be compatible on standard operating systems, including Windows, macOS, and Ubuntu.
关于完全二叉树严谨性补充：完美二叉树是一棵特殊的完全二叉树，完全二叉树的最底层节点可以是满的。
If this pull request (PR) pertains to Chinese-to-English translation, please confirm that you have read the contribution guidelines and complete the checklist below:
If this pull request (PR) is associated with coding or code transpilation, please attach the relevant console outputs to the PR and complete the following checklist: