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Rolling-Hash

LeetCode 1147: Longest Chunked Palindrome Decomposition

2026-07-01·2 mins

LeetCode Hard Dynamic-Programming Greedy Two-Pointers Rolling-Hash String

LeetCode 1147 note: build strings inward from both ends and cut a pair as soon as they match; cutting early is best, and any leftover middle counts as one chunk

LeetCode 1461: Check If a String Contains All Binary Codes of Size K

2026-01-05·2 mins

LeetCode Medium Hash-Table String Bit-Manipulation Rolling-Hash

LeetCode 1461 note: put every length-k substring in a set and check that its size reaches 2^k; the last start is len(s) - k

LeetCode 2156: Find Substring With Given Hash Value

2026-01-04·3 mins

LeetCode Hard Sliding-Window Rolling-Hash String

LeetCode 2156 note: the first character has weight p^0, so sliding right to left needs only multiply by p, add the new character, and subtract the outgoing one times p^k; the modulus may not be prime, so no modular inverse