Formatted question description: https://leetcode.ca/all/2185.html

2185. Counting Words With a Given Prefix (Easy)

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.

A prefix of a string s is any leading contiguous substring of s.

 

Example 1:

Input: words = ["pay","attention","practice","attend"], pref = "at"
Output: 2
Explanation: The 2 strings that contain "at" as a prefix are: "attention" and "attend".

Example 2:

Input: words = ["leetcode","win","loops","success"], pref = "code"
Output: 0
Explanation: There are no strings that contain "code" as a prefix.

 

Constraints:

  • 1 <= words.length <= 100
  • 1 <= words[i].length, pref.length <= 100
  • words[i] and pref consist of lowercase English letters.

Similar Questions:

Solution 1.

// OJ: https://leetcode.com/problems/counting-words-with-a-given-prefix/
// Time: O(NW)
// Space: O(N)
class Solution {
public:
    int prefixCount(vector<string>& A, string pref) {
        int ans = 0;
        for (auto &s : A) {
            if (s.substr(0, pref.size()) == pref) ++ans;
        }
        return ans;
    }
};

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