feat: Add ValidParentheses utility with tests

src/main/java/com/thealgorithms/stacks/ValidParentheses.java

@@ -0,0 +1,37 @@
+package com.thealgorithms.stacks;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.Map;
+
+public final class ValidParentheses {
+
+    private ValidParentheses() {
+        throw new AssertionError("Cannot instantiate utility class");
+    }
+
+    private static final Map<Character, Character> PAIRS = Map.of(')', '(', '}', '{', ']', '[');
+
+    public static boolean isValid(final String s) {
+        if (s == null) {
+            throw new NullPointerException("Input cannot be null");
+        }
+
+        Deque<Character> stack = new ArrayDeque<>();
+        for (char ch : s.toCharArray()) {
+            if (PAIRS.containsValue(ch)) { // opening bracket
+                stack.push(ch);
+            } else if (PAIRS.containsKey(ch)) { // closing bracket
+                // Split logic to satisfy PMD
+                if (stack.isEmpty()) {
+                    return false;
+                }
+                Character top = stack.pop();
+                if (top != PAIRS.get(ch)) {
+                    return false;
+                }
+            }
+        }
+        return stack.isEmpty();
+    }
+}

src/test/java/com/thealgorithms/stacks/ValidParenthesesTest.java

@@ -0,0 +1,31 @@
+package com.thealgorithms.stacks;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+/**
+ * Tests for {@link ValidParentheses}.
+ */
+public class ValidParenthesesTest {
+
+    @ParameterizedTest
+    @CsvSource({"'()', true", "'()[]{}', true", "'{[]}', true", "'', true"})
+    void testValidParentheses(String input, boolean expected) {
+        assertEquals(expected, ValidParentheses.isValid(input));
+    }
+
+    @ParameterizedTest
+    @CsvSource({"'(', false", "')', false", "'([)]', false", "'{[}]', false", "'((()', false"})
+    void testInvalidParentheses(String input, boolean expected) {
+        assertEquals(expected, ValidParentheses.isValid(input));
+    }
+
+    @ParameterizedTest
+    @CsvSource({"null"})
+    void testNullInput(String input) {
+        assertThrows(NullPointerException.class, () -> ValidParentheses.isValid(null));
+    }
+}