Rabin-Karp Algorithm

In the Naive String Matching algorithm, we check whether every substring of the text of the pattern’s size is equal to the pattern or not one by one.

Like the Naive Algorithm, the Rabin-Karp algorithm also check every substring. But unlike the Naive algorithm, the Rabin Karp algorithm matches the hash value of the pattern with the hash value of the current substring of text, and if the hash values match then only it starts matching individual characters. So Rabin Karp algorithm needs to calculate hash values for the following strings.

• Pattern itself
• All the substrings of the text of length m which is the size of pattern.

Given a text T[0. . .n-1] and a pattern P[0. . .m-1], write a function search(char P[], char T[]) that prints all occurrences of P[] present in T[] using Rabin Karp algorithm. You may assume that n > m.

Examples: 

Input:  T[] = “THIS IS A TEST TEXT”, P[] = “TEST”
Output: Pattern found at index 10

Input:  T[] =  “AABAACAADAABAABA”, P[] =  “AABA”
Output: Pattern found at index 0
              Pattern found at index 9
              Pattern found at index 12