1967. Number of Strings That Appear as Substrings in Word

Time: O(p * n)

Space: O(1)

Approach

Count patterns where word.Contains(pattern) is true.

Key Techniques

String problems range from simple character counting to complex pattern matching. Common approaches include two pointers, sliding window, prefix hashing, and the KMP algorithm. In C#, strings are immutable — use StringBuilder for efficient concatenation inside loops.

1967.cs

// Approach: Count patterns where word.Contains(pattern) is true.
// Time: O(p * n) Space: O(1)

public class Solution
{
    public int NumOfStrings(string[] patterns, string word)
    {
        return patterns.Count(pattern => word.Contains(pattern));
    }
}

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