Running KMPTest and RabinKarpTest with fixed formatting

Author: Divyansh Saxena

src/main/java/com/thealgorithms/strings/RabinKarp.java

@@ -33,7 +33,14 @@ public static List<Integer> search(String text, String pattern, int q) {
         int j = 0;
         int i = 0;
 
-        h = (int) Math.pow(ALPHABET_SIZE, m - 1) % q;
+        if (m > n) {
+            return new ArrayList<>();
+        }
+
+        // h = pow(ALPHABET_SIZE, m-1) % q
+        for (i = 0; i < m - 1; i++) {
+            h = (h * ALPHABET_SIZE) % q;
+        }
 
         for (i = 0; i < m; i++) {
             p = (ALPHABET_SIZE * p + pattern.charAt(i)) % q;
@@ -54,10 +61,12 @@ public static List<Integer> search(String text, String pattern, int q) {
             }
 
             if (i < n - m) {
-                t = (ALPHABET_SIZE * (t - text.charAt(i) * h) + text.charAt(i + m)) % q;
+                t = (t - (text.charAt(i) * h) % q);
                 if (t < 0) {
-                    t = (t + q);
+                    t += q;
                 }
+                t = (t * ALPHABET_SIZE) % q;
+                t = (t + text.charAt(i + m)) % q;
             }
         }
         return occurrences;

src/test/java/com/thealgorithms/strings/KMPTest.java

@@ -1,6 +1,7 @@
 package com.thealgorithms.strings;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import java.util.List;
 import org.junit.jupiter.api.Test;
 
@@ -9,7 +10,7 @@ public class KMPTest {
     @Test
     public void testKMPMatcher() {
         assertEquals(List.of(0, 1), KMP.kmpMatcher("AAAAABAAABA", "AAAA"));
-        assertEquals(List.of(0, 2), KMP.kmpMatcher("ABCABC", "ABC"));
+        assertEquals(List.of(0, 3), KMP.kmpMatcher("ABCABC", "ABC"));
         assertEquals(List.of(10), KMP.kmpMatcher("ABABDABACDABABCABAB", "ABABCABAB"));
         assertEquals(List.of(), KMP.kmpMatcher("ABCDE", "FGH"));
         assertEquals(List.of(), KMP.kmpMatcher("A", "AA"));

src/test/java/com/thealgorithms/strings/RabinKarpTest.java

@@ -1,6 +1,7 @@
 package com.thealgorithms.strings;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import java.util.List;
 import org.junit.jupiter.api.Test;
 
@@ -9,7 +10,7 @@ public class RabinKarpTest {
     @Test
     public void testRabinKarpSearch() {
         assertEquals(List.of(0, 1), RabinKarp.search("AAAAABAAABA", "AAAA"));
-        assertEquals(List.of(0, 2), RabinKarp.search("ABCABC", "ABC"));
+        assertEquals(List.of(0, 3), RabinKarp.search("ABCABC", "ABC"));
         assertEquals(List.of(10), RabinKarp.search("ABABDABACDABABCABAB", "ABABCABAB"));
         assertEquals(List.of(), RabinKarp.search("ABCDE", "FGH"));
         assertEquals(List.of(), RabinKarp.search("A", "AA"));