diff --git a/src/main/java/com/thealgorithms/backtracking/NQueens.java b/src/main/java/com/thealgorithms/backtracking/NQueens.java
index 404f677738a0..403102b84066 100644
--- a/src/main/java/com/thealgorithms/backtracking/NQueens.java
+++ b/src/main/java/com/thealgorithms/backtracking/NQueens.java
@@ -4,6 +4,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.logging.Logger;
 
 /**
  * Problem statement: Given a N x N chess board. Return all arrangements in
@@ -41,6 +42,8 @@
  */
 public final class NQueens {
 
+    private static final Logger LOGGER = Logger.getLogger(NQueens.class.getName());
+
     // Store occupied rows for constant time safety check
     private static final Set<Integer> OCROWS = new HashSet<>();
 
@@ -63,13 +66,13 @@ public static void placeQueens(final int queens) {
         List<List<String>> arrangements = new ArrayList<>();
         getSolution(queens, arrangements, new int[queens], 0);
         if (arrangements.isEmpty()) {
-            System.out.println(" no way to place " + queens + " queens on board of size " + queens + "x" + queens);
+            LOGGER.info(" no way to place " + queens + " queens on board of size " + queens + "x" + queens);
         } else {
-            System.out.println("Arrangement for placing " + queens + " queens");
+            LOGGER.info("Arrangement for placing " + queens + " queens");
         }
         for (List<String> arrangement : arrangements) {
-            arrangement.forEach(System.out::println);
-            System.out.println();
+            arrangement.forEach(row -> LOGGER.info(row));
+            LOGGER.info("");
         }
     }
 
diff --git a/src/main/java/com/thealgorithms/stacks/StackPostfixNotation.java b/src/main/java/com/thealgorithms/stacks/StackPostfixNotation.java
index 690f39d36f5c..4a04bb42575e 100644
--- a/src/main/java/com/thealgorithms/stacks/StackPostfixNotation.java
+++ b/src/main/java/com/thealgorithms/stacks/StackPostfixNotation.java
@@ -1,7 +1,8 @@
 package com.thealgorithms.stacks;
 
+import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.Scanner;
-import java.util.Stack;
 import java.util.function.BiFunction;
 
 /**
@@ -35,24 +36,23 @@ private static BiFunction<Integer, Integer, Integer> getOperator(final String op
         }
     }
 
-    private static void performOperation(Stack<Integer> s, final String operationSymbol) {
+    private static void performOperation(Deque<Integer> s, final String operationSymbol) {
         if (s.size() < 2) {
             throw new IllegalArgumentException("exp is not a proper postfix expression (too few arguments).");
         }
         s.push(getOperator(operationSymbol).apply(s.pop(), s.pop()));
     }
 
-    private static void consumeExpression(Stack<Integer> s, final String exp) {
-        Scanner tokens = new Scanner(exp);
-
-        while (tokens.hasNext()) {
-            if (tokens.hasNextInt()) {
-                s.push(tokens.nextInt());
-            } else {
-                performOperation(s, tokens.next());
+    private static void consumeExpression(Deque<Integer> s, final String exp) {
+        try (Scanner tokens = new Scanner(exp)) {
+            while (tokens.hasNext()) {
+                if (tokens.hasNextInt()) {
+                    s.push(tokens.nextInt());
+                } else {
+                    performOperation(s, tokens.next());
+                }
             }
         }
-        tokens.close();
     }
 
     /**
@@ -62,7 +62,7 @@ private static void consumeExpression(Stack<Integer> s, final String exp) {
      * @exception IllegalArgumentException exp is not a valid postix expression.
      */
     public static int postfixEvaluate(final String exp) {
-        Stack<Integer> s = new Stack<>();
+        Deque<Integer> s = new ArrayDeque<>();
         consumeExpression(s, exp);
         if (s.size() != 1) {
             throw new IllegalArgumentException("exp is not a proper postfix expression.");