Lab 14, Task 2
--------------
1.  If we interpret the array as a complete tree, it looks like this:

                       +----+
                       |  5 |
                       +----+
                  ____/      \____
                 /                \
           +----+                  +----+
           |  3 |                  | 12 |
           +----+                  +----+
          /      \                /      \
    +----+        +----+    +----+        +----+
    |  8 |        |  7 |    |  4 |        |  6 |
    +----+        +----+    +----+        +----+


2.  To turn the complete tree into a heap, we take the following steps:

    1.  Sift 12 down. This does not change anything.
    2.  Sift 3 down.

                               +----+
                               |  5 |
                               +----+
                          ____/      \____
                         /                \
                   +----+                  +----+
                   |  8 |                  | 12 |
                   +----+                  +----+
                  /      \                /      \
            +----+        +----+    +----+        +----+
            |  3 |        |  7 |    |  4 |        |  6 |
            +----+        +----+    +----+        +----+

    3.  Sift 5 down.

                               +----+
                               | 12 |
                               +----+
                          ____/      \____
                         /                \
                   +----+                  +----+
                   |  8 |                  |  6 |
                   +----+                  +----+
                  /      \                /      \
            +----+        +----+    +----+        +----+
            |  3 |        |  7 |    |  4 |        |  5 |
            +----+        +----+    +----+        +----+

        At this point, the array looks like this:

           {12, 8, 6, 3, 7, 4, 5}