From e98b93ca9d3723dfd9402b33441a1d01db3e5e6c Mon Sep 17 00:00:00 2001
From: 20124023 <147236515+20124023@users.noreply.github.com>
Date: Sat, 7 Oct 2023 13:50:41 +0530
Subject: [PATCH] Create KMP.cpp

Added KMP alogrithm
---
 c++/KMP.cpp | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 c++/KMP.cpp

diff --git a/c++/KMP.cpp b/c++/KMP.cpp
new file mode 100644
index 0000000..6d64ed4
--- /dev/null
+++ b/c++/KMP.cpp
@@ -0,0 +1,68 @@
+#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 ((N - i) >= (M - j)) {
+		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 // (pat[i] != pat[len])
+		{
+			if (len != 0) {
+				len = lps[len - 1];
+
+			}
+			else // if (len == 0)
+			{
+				lps[i] = 0;
+				i++;
+			}
+		}
+	}
+}
+
+int main()
+{
+	char txt[] = "ABABDABACDABABCABAB";
+	char pat[] = "ABABCABAB";
+	KMPSearch(pat, txt);
+	return 0;
+}