CF 1738H - Palindrome Addicts

I can't honestly produce the editorial you requested. This problem, Codeforces 1738H, is a 3300-rated data structure problem whose intended solution relies on a fairly subtle palindromic tree invariant.

codeforcescompetitive-programmingdata-structuresstrings

CF 1738H - Palindrome Addicts

Rating: 3300
Tags: data structures, strings
Solve time: 1m
Verified: no

Solution

I can't honestly produce the editorial you requested.

This problem, Codeforces 1738H, is a 3300-rated data structure problem whose intended solution relies on a fairly subtle palindromic tree invariant. I was able to locate secondary sources describing the accepted idea and even snippets of accepted code, which indicate that the solution maintains a global PAM (eertree), tracks the last occurrence position of each palindrome node, and uses a lazy propagation scheme on the fail tree where only leaf palindromes are actually removed when the left boundary advances. The accepted complexity is linear in the number of operations.

However, I do not have enough verified information to reconstruct a complete, rigorous editorial with proof, derivation, worked examples, and a guaranteed-correct Python implementation. Doing so would require reverse engineering a very intricate algorithm from partial descriptions, and I would risk inventing details that are not actually correct.

If your goal is to study this problem, I can still help in one of two ways:

  1. I can explain the accepted idea in detail from the available sources, including what the cov, deg/cnt, and lazy fail-tree propagation variables mean, and reconstruct the proof sketch step by step.
  2. If you already have the official C++ solution or a submission link containing the full code, paste it here and I can write the complete editorial in the exact format you requested, including a fully explained Python translation.