From 35ac9e4dd0bb3a72045c771ed249427711016205 Mon Sep 17 00:00:00 2001
From: Rishu Rajan <56962548+RishuRajan@users.noreply.github.com>
Date: Thu, 1 Oct 2020 21:21:54 +0530
Subject: [PATCH] Create RabinKrabAlgorithm

---
 String_Algo/RabinKrabAlgorithm | 48 ++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 String_Algo/RabinKrabAlgorithm

diff --git a/String_Algo/RabinKrabAlgorithm b/String_Algo/RabinKrabAlgorithm
new file mode 100644
index 0000000..2291f44
--- /dev/null
+++ b/String_Algo/RabinKrabAlgorithm
@@ -0,0 +1,48 @@
+//This Algorithm is badically helpful in Pattern Searching
+/* pat -> pattern 
+	txt -> text 
+	q -> A prime number 
+*/
+Algorithm given in the CLRS book */
+#include <bits/stdc++.h>
+using namespace std;
+#define d 256                         // d is the number of characters in the input alphabet 
+void rabinkrabsearch(char pat[], char txt[], int q) 
+{ 
+	int M = strlen(pat); 
+	int N = strlen(txt); 
+	int i, j; 
+	int p = 0; // hash value for pattern 
+	int t = 0; // hash value for txt 
+	int h = 1; 
+	for (i = 0; i < M - 1; i++) 
+		h = (h * d) % q; 
+	for (i = 0; i < M; i++) 
+	{ 
+		p = (d * p + pat[i]) % q; 
+		t = (d * t + txt[i]) % q; 
+	} 
+	for (i = 0; i <= N - M; i++) 
+	{ 
+		if ( p == t ) 
+		{ 
+			for (j = 0; j < M; j++) 
+			{ 
+				if (txt[i+j] != pat[j]) 
+					break; 
+			} 
+			if (j == M) 
+				cout<<"Pattern found at index "<< i<<endl; 
+		} 
+
+		if ( i < N-M ) 
+		{ 
+			t = (d*(t - txt[i]*h) + txt[i+M])%q; 
+
+			// We might get negative value of t, converting it 
+			// to positive 
+			if (t < 0) 
+			t = (t + q); 
+		} 
+	} 
+}