- https://www.geeksforgeeks.org/maximum-width-of-a-binary-tree/
- https://www.geeksforgeeks.org/coin-change-dp-7/
- 找到距离节点最大距离的节点(烧毁的树)- https://stackoverflow.com/questions/52787803/given-a-node-how-long-will-it-take-to-burn-the-whole -二叉树
- OOPS 设计 swiggy- https://www.c-sharpcorner.com/UploadFile/8911c4/singleton-design-pattern-in-C-Sharp/
结果：拒绝