Counting Words With a Given Prefix — LeetCode 2185 Python Solution

The problem

You are given an array of strings words and a string pref. Return the number of strings in words that contain pref as a prefix.

Example

Input

words = ["pay","attention","practice","attend"], pref = "at"

Output

2

Explanation

The 2 strings that contain "at" as a prefix are: "attention" and "attend".

Python solution

class Solution:
    def prefixCount(self, words: List[str], pref: str) -> int:
        return sum(w.startswith(pref) for w in words)

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2185. Counting Words With a Given Prefix is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.

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

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