My LeetCode Journey

https://leetcode.com/problems/lfu-cache/description/ for the items with the same used frequency, the most recently used stay in the front. used sequential method to locate the new position for an item so as to improve performance, the recursive method just sucked in performance!!!.

https://leetcode.com/problems/lru-cache/description/ Using Doubly linked List, hmm, improving the performance is a challenge. UPDATE. by putting the ListItem into the Dictionary as entry, avoided the need of looking for the listitem each time, improved the performance by 50%(from 600ms to 300ms), and from bottom 20% to top 10%.

https://leetcode.com/problems/integer-to-roman/description/ Used Switch statement and pay attention to details

https://leetcode.com/problems/roman-to-integer/description/

https://leetcode.com/problems/reverse-linked-list-ii/description/

https://leetcode.com/problems/reverse-linked-list/description/