Here is source code of the C++ Program to implement Knuth–Morris–Pratt Algorithm (KMP). The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.
/*
* C++ Program to Implement Knuth–Morris–Pratt Algorithm (KMP)
*/
#include <iostream>
#include <cstring>
using namespace std;
void preKMP(string pattern, int f[])
{
int m = pattern.length(), k;
f[0] = -1;
for (int i = 1; i < m; i++)
{
k = f[i - 1];
while (k >= 0)
{
if (pattern[k] == pattern[i - 1])
break;
else
k = f[k];
}
f[i] = k + 1;
}
}
//check whether target string contains pattern
bool KMP(string pattern, string target)
{
int m = pattern.length();
int n = target.length();
int f[m];
preKMP(pattern, f);
int i = 0;
int k = 0;
while (i < n)
{
if (k == -1)
{
i++;
k = 0;
}
else if (target[i] == pattern[k])
{
i++;
k++;
if (k == m)
return 1;
}
else
k = f[k];
}
return 0;
}
int main()
{
string tar = "san and linux training";
string pat = "lin";
if (KMP(pat, tar))
cout<<"'"<<pat<<"' found in string '"<<tar<<"'"<<endl;
else
cout<<"'"<<pat<<"' not found in string '"<<tar<<"'"<<endl;
pat = "sanfoundry";
if (KMP(pat, tar))
cout<<"'"<<pat<<"' found in string '"<<tar<<"'"<<endl;
else
cout<<"'"<<pat<<"' not found in string '"<<tar<<"'"<<endl;
return 0;
}
$ g++ kmp.cpp $ a.out 'lin' found in string 'san and linux training' 'sanfoundry' not found in string 'san and linux training' ------------------ (program exited with code: 1) Press return to continue