refactor: redesign StringMatchFiniteAutomata (#5222)

* refactor

* add test

* fix clang

* fix pmd

* remove main method

* refactor searchPattern with private class

* fix checkstyle

* Update src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java

Co-authored-by: Piotr Idzik <65706193+vil02@users.noreply.github.com>

* Update src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java

Co-authored-by: Piotr Idzik <65706193+vil02@users.noreply.github.com>

* Update src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java

Co-authored-by: Piotr Idzik <65706193+vil02@users.noreply.github.com>

* fix clang

* tests: add more test cases

---------

Co-authored-by: Samuel Facchinello <samuel.facchinello@piksel.com>
Co-authored-by: Piotr Idzik <65706193+vil02@users.noreply.github.com>

src/test/java/com/thealgorithms/others/StringMatchFiniteAutomataTest.java

@@ -0,0 +1,23 @@
+package com.thealgorithms.others;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Set;
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+class StringMatchFiniteAutomataTest {
+
+    @ParameterizedTest
+    @MethodSource("provideTestCases")
+    void searchPattern(String text, String pattern, Set<Integer> expectedOutput) {
+        assertEquals(expectedOutput, StringMatchFiniteAutomata.searchPattern(text, pattern));
+    }
+
+    private static Stream<Arguments> provideTestCases() {
+        return Stream.of(Arguments.of("abcbcabc", "abc", Set.of(0, 5)), Arguments.of("", "abc", Set.of()), Arguments.of("", "", Set.of()), Arguments.of("a", "b", Set.of()), Arguments.of("a", "a", Set.of(0)), Arguments.of("abcdabcabcabcd", "abcd", Set.of(0, 10)), Arguments.of("abc", "bcd", Set.of()),
+            Arguments.of("abcdefg", "xyz", Set.of()), Arguments.of("abcde", "", Set.of(1, 2, 3, 4, 5)), Arguments.of("abcabcabc", "abc", Set.of(0, 3, 6)), Arguments.of("abcabcabc", "abcabcabc", Set.of(0)), Arguments.of("aaabbbaaa", "aaa", Set.of(0, 6)), Arguments.of("abcdefg", "efg", Set.of(4)));
+    }
+}