Count vowel strings in ranges

May 24, 2023


Problem URL: Count vowel strings in ranges

We construct alambdaboolean functionvowelsto assess whether the word qualifies. Then we map the words using this function. Then we construct the prefix sum of the mapped words. Finally, we return the difference between the prefix sum of the end and the prefix sum of the start.

class Solution:
    def vowelStrings(self, words: List[str], queries: List[List[int]]) -> List[int]:
        vowels = lambda w: w[0] in 'aeiou' and w[-1] in 'aeiou'
        words = map(vowels, words)
        prefix_sum = list(itertool.accumulate(words, initial = 0))
        return [prefix_sum[r+1] - prefix_sum[l] for l, r in queries] 

Time complexity: O(n)
Space complexity: O(n)