Create KMPAlgorithm.cpp

gitbeginner2020 · web-flow · commit 9478f18f885d · 2020-10-30T12:49:03.000+05:30
diff --git a/KMPAlgorithm.cpp b/KMPAlgorithm.cpp
@@ -0,0 +1,74 @@
+#include <bits/stdc++.h> 
+
+void computeLPSArray(char* pat, int M, int* lps); 
+void KMPSearch(char* pat, char* txt) 
+{ 
+	int M = strlen(pat); 
+	int N = strlen(txt); 
+
+	int lps[M];  
+	computeLPSArray(pat, M, lps); 
+
+	int i = 0; 
+	int j = 0;  
+	while (i < N) { 
+		if (pat[j] == txt[i]) { 
+			j++; 
+			i++; 
+		} 
+
+		if (j == M) { 
+			printf("Found pattern at index %d ", i - j); 
+			j = lps[j - 1]; 
+		} 
+
+		 
+		else if (i < N && pat[j] != txt[i]) { 
+			
+			if (j != 0) 
+				j = lps[j - 1]; 
+			else
+				i = i + 1; 
+		} 
+	} 
+} 
+
+
+void computeLPSArray(char* pat, int M, int* lps) 
+{ 
+	
+	int len = 0; 
+
+	lps[0] = 0; // lps[0] is always 0 
+
+	
+	int i = 1; 
+	while (i < M) { 
+		if (pat[i] == pat[len]) { 
+			len++; 
+			lps[i] = len; 
+			i++; 
+		} 
+		else 
+		{ 
+			
+			if (len != 0) { 
+				len = lps[len - 1]; 
+
+			} 
+			else 
+			{ 
+				lps[i] = 0; 
+				i++; 
+			} 
+		} 
+	} 
+} 
+
+int main() 
+{ 
+	char txt[] = "ABABDABACDABABCABAB"; 
+	char pat[] = "ABABCABAB"; 
+	KMPSearch(pat, txt); 
+	return 0; 
+} 
