String Matching Algorithm in Data Structure And Algorithm : Practice MCQ Questions & Answers with Explanations

Rabin-Karp algorithm was invented by Richard Karp and Michael Rabin in 1987 for pattern searching in strings.

Rabin-Karp uses hashing. Every substring of the text is converted to a hash value and compared with the hash value of the pattern for fast matching.

When the number of valid shifts v is O(1) and q >= m, the matching time O(n) + O(m(v + n/q)) simplifies to O(n+m).

If q is large enough, spurious hits occur infrequently, making the cost of extra checking low.

Since Rabin-Karp is a pattern detection algorithm, it can be applied to detect plagiarism by searching for matching text patterns across documents.

The worst case running time is Theta((n-m+1)m). We write n-m+1 instead of n-m because there are n-m+1 different positions the pattern can start in the text.

Horner's rule is used to evaluate the pattern in Theta(m): p = P[m] + 10(P[m-1] + 10(P[m-2] + ... + 10(P[2] + 10P[1])...)).

Rabin-Karp Algorithm uses elementary number theoretic notions such as the equivalence of two numbers modulo a third number.

The for loop in the pre-processing step runs m times (length of the pattern). Hence the pre-processing time is Theta(m).

Rabin-Karp is a string matching algorithm proposed by Rabin and Karp. It generalizes to other algorithms and also applies to two-dimensional pattern matching problems.

Using Quick search algorithm, searching starts from the leftmost character and finds the first occurrence of the pattern "CAT" at index 6.

During the searching phase, comparisons can be done in any order. It has quadratic worst-case behaviour but good practical behaviour.

If the pattern occurs in the text, the worst case running time of Boyer-Moore's algorithm is O(mn).

Boyer-Moore's algorithm uses both good-character and bad-character shift tables, whereas Quick search uses only bad-character shift tables.

Quick search algorithm starts searching from the leftmost character to the right, and uses only bad-character shift tables.

The space complexity of the Quick search algorithm is O(n), where n represents the input size.

Quick search algorithm uses only bad-character shift tables, which is one of the reasons for its increased speed over Boyer-Moore's algorithm.

The time complexity of the Quick search algorithm is O(m+n), which is proven to be faster than Boyer-Moore's algorithm.

Quick search algorithm was developed to overcome the drawbacks of Boyer-Moore's algorithm, improving speed and efficiency.

Quick search algorithm is the fastest algorithm in the string matching field, whereas linear search searches for an element in an array sequentially.