Dynamic Programming - Longest Palindromic Subsequence
466C-Number Of Ways
Instead of binary search, a suffix sum array of count can be created for quering for each $l[i]$. Reducing complexity from $O(n\log{}n)$ to $O(n)$.
1114D-Flood Fill
One interesting idea to note was, the answer can be calculated using longest palindromic subsequence. Which inturn can be calculated by find LCS between array and it’s reverse.