|887|鸡蛋掉落|[dp1](./hard/dp/887.鸡蛋掉落(TLE).py), [dp + binarySearch](./hard/dp/887.鸡蛋掉落(dp+binarySearch).py), [dp2-todo](./)|dp|

|99|恢复二叉搜索树|[O(n)traversal](./hard/tree/99.恢复二叉搜索树_O(n).py), [refine traversal 解法](./hard/tree/99.恢复二叉搜索树(refine).py), [Morris算法](./tree/99.恢复二叉搜索树.py)|tree|

|72|编辑距离|[dp](./hard/dp/72.编辑距离.py)|dp|

|42|接雨水|[dp](./hard/array/42.接雨水.py)|array|

|23|合并k个排序链表|[priority_queue](./hard/priority_queue/23.合并k个排序链表.py)|priority_queue|