Moved StackPostfixNotation.java from the Others section to the Stack section (#4372)

* Moved StackPostfixNotation.java from the Others section to the Stack section

* Put all stack related algo in a separate stack directory in the algorithms directory. The stack directory under data-structures now only contains various implementations of the stack data structure.

* formatted files

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

@@ -0,0 +1,58 @@
+package com.thealgorithms.stacks;
+
+import java.util.Stack;
+
+public class DecimalToAnyUsingStack {
+
+    public static void main(String[] args) {
+        assert convert(0, 2).equals("0");
+        assert convert(30, 2).equals("11110");
+        assert convert(30, 8).equals("36");
+        assert convert(30, 10).equals("30");
+        assert convert(30, 16).equals("1E");
+    }
+
+    /**
+     * Convert decimal number to another radix
+     *
+     * @param number the number to be converted
+     * @param radix the radix
+     * @return another radix
+     * @throws ArithmeticException if <tt>number</tt> or <tt>radius</tt> is
+     * invalid
+     */
+    private static String convert(int number, int radix) {
+        if (radix < 2 || radix > 16) {
+            throw new ArithmeticException(String.format("Invalid input -> number:%d,radius:%d", number, radix));
+        }
+        char[] tables = {
+            '0',
+            '1',
+            '2',
+            '3',
+            '4',
+            '5',
+            '6',
+            '7',
+            '8',
+            '9',
+            'A',
+            'B',
+            'C',
+            'D',
+            'E',
+            'F',
+        };
+        Stack<Character> bits = new Stack<>();
+        do {
+            bits.push(tables[number % radix]);
+            number = number / radix;
+        } while (number != 0);
+
+        StringBuilder result = new StringBuilder();
+        while (!bits.isEmpty()) {
+            result.append(bits.pop());
+        }
+        return result.toString();
+    }
+}