https://leetcode.com/problems/freedom-trail/description/

Min steps to produce key by rotating ring #hard #dynamic_programming #recursion #hash_map

https://leetcode.com/problems/parsing-a-boolean-expression/description/


Parse boolean expression #hard #stack #recursion

https://leetcode.com/problems/flip-equivalent-binary-trees/description/


Are trees flip-equal #medium #recursion #dfs

https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves/description

Lowest common ancestor of deepest tree nodes #medium #recursion