Elixir Christmas Tree Puzzle

The page sets a short Elixir coding challenge: print a Christmas tree with a 9-row triangle of 0 characters, a * at the top, and an H trunk at the bottom. The star and trunk must line up with the tree, and the full output is 11 rows high.

Reading notes

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• The triangle has to be properly indented so each row stays centered above the next.
• The top * and bottom H are separate rows aligned with the tree.
• The shortest solution wins, though creative versions can receive an honourable mention.
• Submissions were requested as GitHub issue comments, together with a Twitter handle.
• The article then presents several submitted solutions and explains how they work.
• The winning solution uses an anonymous function and the Erlang :string.centre/2 function.
• One solution uses io.format/2 and io_lib.format/2 to build the rows.
• Other solutions rely on lists, comprehensions, List.duplicate/2, IO.puts, or string functions such as String.rjust/2 and String.duplicate/2.
• The bonus section shows more decorative versions, including a colored tree with flashing lights.