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rabin karp

Pleasant Penguin answered on April 5, 2022 Popularity 9/10 Helpfulness 1/10

answer rabin karp

related Rabin karp

rabin karp

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/* Following program is a C implementation of Rabin Karp
Algorithm given in the CLRS book */
#include<stdio.h>
#include<string.h>
 
// d is the number of characters in the input alphabet
#define d 256
 
/* pat -> pattern
    txt -> text
    q -> A prime number
*/
void search(char pat[], char txt[], int q)
{
    int M = strlen(pat);
    int N = strlen(txt);
    int i, j;
    int p = 0; // hash value for pattern
    int t = 0; // hash value for txt
    int h = 1;
 
    // The value of h would be "pow(d, M-1)%q"
    for (i = 0; i < M-1; i++)
        h = (h*d)%q;
 
    // Calculate the hash value of pattern and first
    // window of text
    for (i = 0; i < M; i++)
    {
        p = (d*p + pat[i])%q;
        t = (d*t + txt[i])%q;
    }
 
    // Slide the pattern over text one by one
    for (i = 0; i <= N - M; i++)
    {
 
        // Check the hash values of current window of text
        // and pattern. If the hash values match then only
        // check for characters one by one
        if ( p == t )
        {
            /* Check for characters one by one */
            for (j = 0; j < M; j++)
            {
                if (txt[i+j] != pat[j])
                    break;
            }
 
            // if p == t and pat[0...M-1] = txt[i, i+1, ...i+M-1]
            if (j == M)
                printf("Pattern found at index %d \n", i);
        }
 
        // Calculate hash value for next window of text: Remove
        // leading digit, add trailing digit
        if ( i < N-M )
        {
            t = (d*(t - txt[i]*h) + txt[i+M])%q;
 
            // We might get negative value of t, converting it
            // to positive
            if (t < 0)
            t = (t + q);
        }
    }
}
 
/* Driver Code */
int main()
{
    char txt[] = "GEEKS FOR GEEKS";
    char pat[] = "GEEK";
   
      // A prime number
    int q = 101;
   
      // function call
    search(pat, txt, q);
    return 0;
}

Popularity 9/10 Helpfulness 1/10 Language whatever

Source: www.geeksforgeeks.org

Tags: rabin-karp whatever

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Contributed on Apr 05 2022

Pleasant Penguin

0 Answers Avg Quality 2/10

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Rabin karp

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public class RabinKarp {
  public final static int d = 10;
  static void search(String pattern, String str, int q) {
    int m = pattern.length();
    int n = str.length();
    int i, j;
    int p = 0;
    int t = 0;
    int h = 1;

    for (i = 0; i < m - 1; i++)
      h = (h * d) % q;
    // Calculate hash value for pattern and text
    for (i = 0; i < m; i++) {
      p = (d * p + pattern.charAt(i)) % q;
      t = (d * t + str.charAt(i)) % q;
    }

    // Find the match
    for (i = 0; i <= n - m; i++) {
      if (p == t) {
        for (j = 0; j < m; j++) {
          if (str.charAt(i + j) != pattern.charAt(j))
            break;
        }
        if (j == m)
          System.out.println("Pattern is found at position: " + (i + 1));
      }

      if (i < n - m) {
        t = (d * (t - str.charAt(i) * h) + str.charAt(i + m)) % q;
        if (t < 0)
          t = (t + q);
      }
    }
  }
  public static void main(String[] args) {
    String str = "ABCCDDAEFG";
    String pattern = "CDD";
    int q = 13;
    search(pattern, str, q);
  }
}

Popularity 8/10 Helpfulness 1/10 Language java

Source: favtutor.com

Tags: rabin-karp java rabin

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Contributed on Nov 16 2022

Itchy Impala

0 Answers Avg Quality 2/10

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