Substring Search Scripting | Dataford Interview Questions

Wolters Kluwer deployment tooling may need to detect a marker such as "ERROR" or "rollback" within a large log string. Implement a function that returns True when a pattern occurs in the text and False otherwise.

The match must be case-sensitive, and the pattern may occur at any position, including the beginning or end of the text. To support large logs efficiently, implement the Knuth-Morris-Pratt (KMP) algorithm rather than repeatedly comparing every possible substring from scratch.

Formal Specification

Implement contains_substring(text, pattern).

Input: text and pattern, both strings containing printable ASCII characters.
Output: A boolean. Return True if pattern is a contiguous substring of text; otherwise return False.
An empty pattern is considered present in every text, including an empty text.

Constraints

0 <= len(text) <= 10^6
0 <= len(pattern) <= 10^5
Both strings contain printable ASCII characters
Matching is case-sensitive
An empty pattern is considered present
The required time complexity is O(len(text) + len(pattern))

Function Signature

def contains_substring(text, pattern):

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