Number of Strings That Appear as Substrings in Word

Given an array of strings patterns and a string word, return the number of strings in patterns that exist as a substring in word.

A substring is a contiguous sequence of characters within a string.

Example 1:

Input: patterns = ["a","abc","bc","d"], word = "abc"
Output: 3
Explanation:

• "a" appears as a substring in "abc".
• "abc" appears as a substring in "abc".
• "bc" appears as a substring in "abc".
• "d" does not appear as a substring in "abc". 3 of the strings in patterns appear as a substring in word.

Example 2:

Input: patterns = ["a","b","c"], word = "aaaaabbbbb"
Output: 2
Explanation:

• "a" appears as a substring in "aaaaabbbbb".
• "b" appears as a substring in "aaaaabbbbb".
• "c" does not appear as a substring in "aaaaabbbbb". 2 of the strings in patterns appear as a substring in word.

Example 3:

Input: patterns = ["a","a","a"], word = "ab"
Output: 3
Explanation: Each of the patterns appears as a substring in word "ab".

Constraints:

• 1 <= patterns.length <= 100
• 1 <= patterns[i].length <= 100
• 1 <= word.length <= 100
• patterns[i] and word consist of lowercase English letters.

SOLUTION:

from collections import Counter

class Solution:
    def numOfStrings(self, patterns: List[str], word: str) -> int:
        n = len(word)
        patterns = Counter(patterns)
        lens = set([len(p) for p in patterns])
        ctr = 0
        for l in lens:
            for i in range(0, n - l + 1):
                curr = word[i:i+l]
                if curr in patterns:
                    ctr += patterns[curr]
                    del patterns[curr]
        return ctr