KMP Algorithm

KMP_Algorithm.cpp

@@ -0,0 +1,68 @@
+#include<bits/stdc++.h>
+using namespace std;
+void getLPS(string pat,int m,int lps[]);
+void KMPpatternSearch(string txt,string pat)
+{
+	int n=txt.size();
+	int m=pat.size();
+	int i=0,j=0;
+	int lps[m];
+	getLPS(pat,m,lps);
+	while(i<n)
+	{
+		if(txt[i]==pat[j])
+		{
+			i++;
+			j++;
+		}
+		 if(j==m)
+		{
+		cout<<"Pattern found at = "<<i-m<<endl;
+	    j=lps[j-1];
+		}
+		else if(i<n&&txt[i]!=pat[j])
+		{
+			if(j>0)
+			j=lps[j-1];
+			else
+			i=i+1;
+		}
+	}
+}
+void getLPS(string pat,int m,int lps[])
+{
+	int len=0,i=1;
+	lps[0]=0;
+	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++;
+			}
+		}
+	}
+	for(int j=0;j<m;j++)
+	cout<<lps[j]<<" ";
+
+}
+int main()
+{
+	string txt,pat;
+	getline(cin,txt);
+	getline(cin,pat);
+	KMPpatternSearch(txt,pat);
+	return 0;
+}