test: RegexMatchingTest (#5403)

* test: RegexMatchingTest

* checkstyle: fix formatting

---------

Co-authored-by: alxkm <alx@alx.com>
Co-authored-by: Andrii Siriak <siryaka@gmail.com>

src/main/java/com/thealgorithms/dynamicprogramming/RegexMatching.java

@@ -6,17 +6,28 @@ package com.thealgorithms.dynamicprogramming;
  * cover the entire text ?-> matches single characters *-> match the sequence of
  * characters
  *
- * For calculation of Time and Space Complexity. Let N be length of src and M be
+ * For calculation of Time and Space Complexity. Let N be length of src and M be length of pat
- * length of pat
  *
+ * Memoization vs Tabulation : https://www.geeksforgeeks.org/tabulation-vs-memoization/
+ * Question Link : https://practice.geeksforgeeks.org/problems/wildcard-pattern-matching/1
  */
 public final class RegexMatching {
     private RegexMatching() {
     }
 
-    // Method 1: Using Recursion
+    /**
-    // Time Complexity=0(2^(N+M)) Space Complexity=Recursion Extra Space
+     * Method 1: Determines if the given source string matches the given pattern using a recursive approach.
-    static boolean regexRecursion(String src, String pat) {
+     * This method directly applies recursion to check if the source string matches the pattern, considering
+     * the wildcards '?' and '*'.
+     *
+     * Time Complexity: O(2^(N+M)), where N is the length of the source string and M is the length of the pattern.
+     * Space Complexity: O(N + M) due to the recursion stack.
+     *
+     * @param src The source string to be matched against the pattern.
+     * @param pat The pattern containing wildcards ('*' matches a sequence of characters, '?' matches a single character).
+     * @return {@code true} if the source string matches the pattern, {@code false} otherwise.
+     */
+    public static boolean regexRecursion(String src, String pat) {
         if (src.length() == 0 && pat.length() == 0) {
             return true;
         }
@@ -50,8 +61,19 @@ public final class RegexMatching {
         return ans;
     }
 
-    // Method 2: Using Recursion and breaking string using virtual index
+    /**
-    // Time Complexity=0(2^(N+M)) Space Complexity=Recursion Extra Space
+     * Method 2: Determines if the given source string matches the given pattern using recursion.
+     * This method utilizes a virtual index for both the source string and the pattern to manage the recursion.
+     *
+     * Time Complexity: O(2^(N+M)) where N is the length of the source string and M is the length of the pattern.
+     * Space Complexity: O(N + M) due to the recursion stack.
+     *
+     * @param src The source string to be matched against the pattern.
+     * @param pat The pattern containing wildcards ('*' matches a sequence of characters, '?' matches a single character).
+     * @param svidx The current index in the source string.
+     * @param pvidx The current index in the pattern.
+     * @return {@code true} if the source string matches the pattern, {@code false} otherwise.
+     */
     static boolean regexRecursion(String src, String pat, int svidx, int pvidx) {
         if (src.length() == svidx && pat.length() == pvidx) {
             return true;
@@ -83,9 +105,21 @@ public final class RegexMatching {
         return ans;
     }
 
-    // Method 3: Top-Down DP(Memoization)
+    /**
-    // Time Complexity=0(N*M) Space Complexity=0(N*M)+Recursion Extra Space
+     * Method 3: Determines if the given source string matches the given pattern using top-down dynamic programming (memoization).
-    static boolean regexRecursion(String src, String pat, int svidx, int pvidx, int[][] strg) {
+     * This method utilizes memoization to store intermediate results, reducing redundant computations and improving efficiency.
+     *
+     * Time Complexity: O(N * M), where N is the length of the source string and M is the length of the pattern.
+     * Space Complexity: O(N * M) for the memoization table, plus additional space for the recursion stack.
+     *
+     * @param src The source string to be matched against the pattern.
+     * @param pat The pattern containing wildcards ('*' matches a sequence of characters, '?' matches a single character).
+     * @param svidx The current index in the source string.
+     * @param pvidx The current index in the pattern.
+     * @param strg A 2D array used for memoization to store the results of subproblems.
+     * @return {@code true} if the source string matches the pattern, {@code false} otherwise.
+     */
+    public static boolean regexRecursion(String src, String pat, int svidx, int pvidx, int[][] strg) {
         if (src.length() == svidx && pat.length() == pvidx) {
             return true;
         }
@@ -120,8 +154,18 @@ public final class RegexMatching {
         return ans;
     }
 
-    // Method 4: Bottom-Up DP(Tabulation)
+    /**
-    // Time Complexity=0(N*M) Space Complexity=0(N*M)
+     * Method 4: Determines if the given source string matches the given pattern using bottom-up dynamic programming (tabulation).
+     * This method builds a solution iteratively by filling out a table, where each cell represents whether a substring
+     * of the source string matches a substring of the pattern.
+     *
+     * Time Complexity: O(N * M), where N is the length of the source string and M is the length of the pattern.
+     * Space Complexity: O(N * M) for the table used in the tabulation process.
+     *
+     * @param src The source string to be matched against the pattern.
+     * @param pat The pattern containing wildcards ('*' matches a sequence of characters, '?' matches a single character).
+     * @return {@code true} if the source string matches the pattern, {@code false} otherwise.
+     */
     static boolean regexBU(String src, String pat) {
         boolean[][] strg = new boolean[src.length() + 1][pat.length() + 1];
         strg[src.length()][pat.length()] = true;
@@ -153,15 +197,4 @@ public final class RegexMatching {
         }
         return strg[0][0];
     }
-
-    public static void main(String[] args) {
-        String src = "aa";
-        String pat = "*";
-        System.out.println("Method 1: " + regexRecursion(src, pat));
-        System.out.println("Method 2: " + regexRecursion(src, pat, 0, 0));
-        System.out.println("Method 3: " + regexRecursion(src, pat, 0, 0, new int[src.length()][pat.length()]));
-        System.out.println("Method 4: " + regexBU(src, pat));
-    }
 }
-// Memoization vs Tabulation : https://www.geeksforgeeks.org/tabulation-vs-memoization/
-// Question Link : https://practice.geeksforgeeks.org/problems/wildcard-pattern-matching/1

src/test/java/com/thealgorithms/dynamicprogramming/RegexMatchingTest.java

@@ -0,0 +1,43 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+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;
+
+public class RegexMatchingTest {
+
+    private record RegexTestCase(String s, String p, boolean expected) {
+    }
+
+    private static Stream<Arguments> provideTestCases() {
+        return Stream.of(Arguments.of(new RegexTestCase("aa", "*", true)), Arguments.of(new RegexTestCase("aa", "a*", true)), Arguments.of(new RegexTestCase("aa", "a", false)), Arguments.of(new RegexTestCase("cb", "?b", true)), Arguments.of(new RegexTestCase("cb", "?a", false)),
+            Arguments.of(new RegexTestCase("adceb", "*a*b", true)), Arguments.of(new RegexTestCase("acdcb", "a*c?b", false)), Arguments.of(new RegexTestCase("", "*", true)), Arguments.of(new RegexTestCase("", "", true)));
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideTestCases")
+    void testRegexRecursionMethod1(RegexTestCase testCase) {
+        assertEquals(testCase.expected(), RegexMatching.regexRecursion(testCase.s(), testCase.p()));
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideTestCases")
+    void testRegexRecursionMethod2(RegexTestCase testCase) {
+        assertEquals(testCase.expected(), RegexMatching.regexRecursion(testCase.s(), testCase.p(), 0, 0));
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideTestCases")
+    void testRegexRecursionMethod3(RegexTestCase testCase) {
+        assertEquals(testCase.expected(), RegexMatching.regexRecursion(testCase.s(), testCase.p(), 0, 0, new int[testCase.s().length()][testCase.p().length()]));
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideTestCases")
+    void testRegexBottomUp(RegexTestCase testCase) {
+        assertEquals(testCase.expected(), RegexMatching.regexBU(testCase.s(), testCase.p()));
+    }
+}