2026-02-23 15:14:19 +0000 UTC

Check If a String Contains All Binary Codes of Size K
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Code

class Solution:
    def hasAllCodes(self, s: str, k: int) -> bool:
        req = 1 << k
        seen = [False] * req
        mask = req - 1
        h = 0

        for i, ch in enumerate(s):
            h = ((h << 1) & mask) | (ord(ch) & 1)

            if i >= k - 1 and not seen[h]:
                seen[h] = True
                req -= 1
                if req == 0:
                    return True

        return False