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Tested Python solution for LeetCode 2185 with 15 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 2185 # by problem number
lcpy gen -s counting_words_with_a_given_prefix # by problem name
words and a string pref.
Return the number of strings in words that contain pref as a prefix.
A prefix of a string s is any leading contiguous substring of s.
Input: words = ["pay","attention","practice","attend"], pref = "at"
Output: 2
Explanation: The 2 strings that contain "at" as a prefix are: "attention" and "attend".
Input: words = ["leetcode","win","loops","success"], pref = "code"
Output: 0
Explanation: There are no strings that contain "code" as a prefix.
class Solution:
# Time: O(sum(len(w) for w in words) * len(pref)) worst case via startswith
# Space: O(1)
def prefix_count(self, words: list[str], pref: str) -> int:
return sum(1 for word in words if word.startswith(pref))
| Time | Space |
|---|---|
| O(sum(len(w) for w in words) * len(pref)) worst case via startswith | O(1) |