MTech VTU Advanced Algorithm Lab (2nd sem)
Design, develop, and write a program to solve String matching problem using Rabin Karp algorithm and determine its performance.
Design, develop, and write a program to solve String matching problem using Rabin Karp algorithm and determine its performance.
#include<stdio.h>
#include<string.h>
#define d 256
void search(char pat[], char txt[], int q)
{
int
M = strlen(pat);
int N = strlen(txt);
int i, j;
int p = 0;
int t = 0;
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)
printf("\nPattern
found at index %d", i);
}
if ( i < N-M )
{
t = (d*(t - txt[i]*h) +
txt[i+M]) % q;
if (t < 0)
t = (t + q);
}
}
}
int main()
{
char txt[30], pat[30];
int q = 101; // A prime number
printf("\n Enter the text:");
gets(txt);
printf("\n Enter the
pattern:");
gets(pat);
search(pat,
txt, q);
return 0;
}
Output:
Enter the
text: abacbaaababa
Enter the
pattern: aba
Pattern found at index 0
Pattern found at index 7
Pattern found at index 9
