2025-08-17 09:39:05 +0000 UTC

class Solution:
    def countWords(self, words1: List[str], words2: List[str]) -> int:
        freqs = defaultdict(lambda: (0, 0))
        for word in words1:
            freq1, _ = freqs[word]
            if freq1 in (0, 1):
                freqs[word] = (freq1 + 1, 0)
        for word in words2:
            freq1, freq2 = freqs[word]
            if freq2 in (0, 1):
                freqs[word] = (freq1, freq2 + 1)
        res = 0
        for freq1, freq2 in freqs.values():
            if freq1 == freq2 == 1:
                res += 1
        return res