Count Common Words With One Occurrence — LeetCode 2085 Python Solution

The problem

Given two string arrays words1 and words2, return the number of strings that appear exactly once in each of the two arrays.

Example

Input

words1 = ["leetcode","is","amazing","as","is"], words2 = ["amazing","leetcode","is"]

Output

2

Explanation

- "leetcode" appears exactly once in each of the two arrays. We count this string.

Python solution

class Solution:
    def countWords(self, words1: List[str], words2: List[str]) -> int:
        cnt1 = Counter(words1)
        cnt2 = Counter(words2)
        return sum(v == 1 and cnt2[w] == 1 for w, v in cnt1.items())

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2085. Count Common Words With One Occurrence is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table and Counting.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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