[JAVA-10384] Amendment to cover all cases + Added Unit tests (#12169)

Co-authored-by: panagiotiskakos <panagiotis.kakos@libra-is.com>

algorithms-miscellaneous-6/src/main/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingDeque.java

@@ -31,6 +31,6 @@ public class BalancedBracketsUsingDeque {
             }
         }
 
-        return true;
+        return deque.isEmpty();
     }
 }

algorithms-miscellaneous-6/src/test/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingDequeUnitTest.java

@@ -49,6 +49,12 @@ public class BalancedBracketsUsingDequeUnitTest {
         assertThat(result).isFalse();
     }
 
+    @Test
+    public void givenAnotherEvenLengthUnbalancedString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{{}(");
+        assertThat(result).isFalse();
+    }
+
     @Test
     public void givenEvenLengthBalancedString_whenCheckingForBalance_shouldReturnTrue() {
         boolean result = balancedBracketsUsingDeque.isBalanced("{[()]}");

algorithms-miscellaneous-6/src/test/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingStringUnitTest.java

@@ -49,6 +49,12 @@ public class BalancedBracketsUsingStringUnitTest {
         assertThat(result).isFalse();
     }
 
+    @Test
+    public void givenAnotherEvenLengthUnbalancedString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingString.isBalanced("{{}(");
+        assertThat(result).isFalse();
+    }
+
     @Test
     public void givenEvenLengthBalancedString_whenCheckingForBalance_shouldReturnTrue() {
         boolean result = balancedBracketsUsingString.isBalanced("{[()]}");