Simple X-mas tree

Doc/Sd1/statements.xml

@@ -9,6 +9,122 @@
          xmlns:db="http://docbook.org/ns/docbook">
   <title>Statements</title>
 
+  <section xml:id="sw1SectXmas">
+    <title>Merry Xmas</title>
+
+    <qandaset defaultlabel="qanda" xml:id="sd1QandaXmasTree">
+      <qandadiv>
+        <qandaentry>
+          <question>
+            <para>Write an application to print an ASCII art Xmas tree.
+            Provide a configurable parameter which allows for controlling the
+            tree's size. The following example shows a tree spanning 6 rows
+            excluding top (X) and bottom (###):</para>
+
+            <programlisting language="none">      X
+      *
+     ***
+    *****
+   *******
+  *********
+ ***********
+     ###
+     ###</programlisting>
+
+            <tip>
+              <para>The following example printing a triangle may serve as a
+              starting point:</para>
+
+              <informaltable border="1">
+                <colgroup width="47%"/>
+
+                <colgroup width="5%"/>
+
+                <colgroup width="48%"/>
+
+                <tr>
+                  <td valign="top"><programlisting language="none">   public static void main(String[] args) {
+
+      int numberOfRows = 7;
+      
+      for (int row = 0; row &lt; numberOfRows; row++) { 
+         for (int x = 0; x &lt;row; x++) {
+            System.out.print('*');
+         }
+         System.out.println('*');
+      }
+   }</programlisting></td>
+
+                  <td align="center">⟹</td>
+
+                  <td valign="top"><programlisting language="none">*
+**
+***
+****
+*****
+******
+*******</programlisting></td>
+                </tr>
+              </informaltable>
+            </tip>
+          </question>
+
+          <answer>
+            <programlisting language="none">   public static void main(String[] args) {      
+      
+      // Example: 6 rows, tree's body loop index ranging from 0 to 5
+      //
+      //           X            The tree's top.
+      //  0        *
+      //  1       ***       
+      //  2      *****      
+      //  3     *******         The tree's body.
+      //  4    *********  
+      //  5   ***********
+      //          III           The tree's two bottom trunk lines.
+      //          III      
+      
+      final int numberOfRows = 6;                        // You may easily change this value.
+      
+      // Part one: the tree's top
+      //
+      for (int x = 0; x &lt; numberOfRows; x++) {           // Printing the tree's top. We need 
+         System.out.print(' ');                          // numberOfRows preceding spaces
+      }                                                  // before printing the
+      System.out.println("X");                           // 'X' (top) character.
+      
+      // Part two: The tree's body
+      //
+      for (int row = 0; row &lt; numberOfRows ; row++) {    // Outer loop printing the tree's body.
+         
+         for (int x = 0; x &lt; numberOfRows - row;x++) {   // Starting each line with (numberOfRows - row)
+            System.out.print(' ');                       // space characters ...
+         }
+         
+         for (int x = 0; x &lt; 2 * row + 1; x ++) {        // .. then printing (2*row+1) body ('*') characters ...
+         System.out.print('*'); // May try '▲' instead
+         }
+         System.out.print("\n");                         // ... and finally terminating the current body row.
+      }
+      
+      // Part three: The tree's bottom trunk
+      //
+      for (int x = 0; x &lt; numberOfRows-1; x++) {         // Preparing the first line of bottom trunk part ...
+         System.out.print(' ');
+      }
+      System.out.println("###");                         // ... finished.
+      
+      for (int x = 0; x &lt; numberOfRows-1; x++) {         //  Preparing the second line of bottom trunk part ...
+         System.out.print(' ');
+      }
+      System.out.println("###");                         // ... finished.
+   }</programlisting>
+          </answer>
+        </qandaentry>
+      </qandadiv>
+    </qandaset>
+  </section>
+
   <section xml:id="sd1SectSquareNumberTable">
     <title>A table of square numbers</title>
 
@@ -189,8 +305,8 @@
               different values just by changing tis single value.</para>
 
               <tip>
-                <para>You'll need a loop nested within an outer one like:
-                </para>
+                <para>You'll need a loop nested within an outer one
+                like:</para>
 
                 <programlisting language="none">for (int y=0; &lt; limit; y++){