Upload files to 'Exercise 6 - Karp-Rabin String Search (Week 7)'

Exercise 6 - Karp-Rabin String Search (Week 7)/Ex6.txt

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+ATTGGTAAATACGGCTGTACGGTGCCGACTAAGCGGAATAGCCTACCACGTTACGGTATCTTCTTGCAAGTGTATTCTCGCACCTTAATTGTATCGGGAAGTAGGTTATGATGATAGAGACCCCCCCGGCACAAAACTTTCGGTAAGTGGAGCGCCCGACTGGCCGCCGGGATCAGAACGAACGATGCCCAGGGGCCGGCGGGCGATGAGCGACTTCGACGACCCAGGCTACGAATTCCCTGCCGACCCATTCTTGATGAAAAGCCCTGCTTCGGGACTGTCTGAAAATCTGTTTTTAGGGCACTTTGTCTCTTTCAAGGCAGTCCCTGGCGTGCTATCCGCATGGACATATCGCCATGACGACGATTGACCAGAGCAGCCTCAAAGTGGCAAATTCCTAACAGGCACCTACTTAGATGCGACGAGTAAAGCGCCGGGAAAGGTAACATGAACGGTTGAAAAATACAACGAGATACCGGGAGGGAAACTAGCAGATGCTCGGACATAGCACTCTGGGTCGCCGGAGGTGCCAAGTTAAAGCGCAACCAAGACTGGATCTGCCATCTCCTAAAGGGGAGCTGCTACCTACACATACTGTTCTCGTTGGATCGACCTTGCGTATATCCTGGGATCCACTACTTTGAATCACAGGAGCTACCCCTCGTATGGCTGATTGGCGGCCACCGTTTCCCGACAGACTGTCTGCTACGTTAGGTTACTAAATGACCGACAGCTAGACCGGGAGGTCAATTTTGGATTTCTATAGTCATCAACCACTGCGGTTGGCATCCCATAACCCGGCGCACTATGCTGCACACGAGGACTGTCAATAGCTTCGGCCACGCAGGCTAACGGCTCGAGGCATGGGTAAGGTTGCTCGAGCCGGCGCCACACCAGCTCTTACTCCATATCAGCCGGCGCGACCACAGGGAGGGCCAAAAGCGTGCGAAACATGCATCTACTCTCTCTACTCGCCGTCAAGCCAATTGTAGGACGGCAAATCGACATCTATGATCTTTGATCG
+AGCTA

Exercise 6 - Karp-Rabin String Search (Week 7)/ex6.c

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+/* License: AGPLv3 or later. https://www.gnu.org/licenses/licenses.html
+ * 
+ * Exercise 6 - Karp-Rabin String Search (Week 7)
+ * Name: Manish
+ * Student Login: *****
+ * 
+ * Compile as:
+ * $ gcc -std=c11 -Wall -o ex6 ex6.c
+ * 
+ * NOTE: There is error that using some small no. like 500 give incorrect (incomplete) results. Still not figured out why.
+ */ 
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+char t[5001];
+char s[11];
+int t_len = 0;
+int s_len = 0;
+unsigned long prime = 5;
+unsigned long mod = 18446744073709551557UL; // prime < 2^64
+unsigned long precomputed_prime_exponent = 1;
+
+int main(void)
+{
+    printf("Enter file name: ");
+    char filename[257];
+    // Assuming filename/file path won't be longer than 256 characters
+    scanf("%256s", filename);
+
+    FILE* file = fopen(filename, "r");
+    if (!file)
+    {
+        perror(filename);
+        exit(EXIT_FAILURE);
+    }
+
+    fscanf(file, "%5000s %10s", t, s);
+    t_len = strlen(t);
+    s_len = strlen(s);
+
+    unsigned long t_hash = t[0]%5;
+    unsigned long s_hash = s[0]%5;
+
+    for (int i=1; i < s_len; i++)
+    {
+        precomputed_prime_exponent = (precomputed_prime_exponent*prime)%mod;
+        t_hash = (((prime*t_hash)%mod) + (t[i]%5))%mod;
+        s_hash = (((prime*s_hash)%mod)+ (s[i]%5))%mod;
+    }
+
+    for (int i=0; i < t_len-s_len; i++)
+    {
+        if (t_hash == s_hash)
+        {
+            if (strncmp(&t[i], s, s_len) == 0)
+                printf("%d ", i);
+        }
+        // %5 for characters and %mod every + & * part of equation
+        t_hash = (
+            (((prime*
+            (t_hash -
+            ((precomputed_prime_exponent*(t[i]%5))%mod)
+            ))%mod) +
+            (t[i+s_len]%5))
+            %mod);
+    }
+    printf("\n");
+
+    fclose(file);
+
+    return 0;
+}

Exercise 6 - Karp-Rabin String Search (Week 7)/makefile

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+ex6:	ex6.c
+	gcc -std=c11 -Wall -o ex6 ex6.c