# Alphabet Rangoli Generator
# --------------------------
# This program prints a geometric alphabet pattern ("rangoli") of size N.
# The pattern uses letters descending from the alphabet starting at:
# 'a' + (N - 1)
# For example, N = 5 → start letter 'e'.
# Returns the sequence of characters for a given row index.
def row_pattern(n, row)
# Build the alphabet normally: ["a", "b", "c", ...]
alphabet = ('a'..'z').to_a
# Select the first n letters, but we want the *highest* letter at index 0.
# Example: n = 5 → ["e", "d", "c", "b", "a"]
letters = alphabet[0, n].reverse
# Take letters down to the current row
left_half = letters[0..row]
# Mirror the slice except the last element
full_row = left_half + left_half[0...-1].reverse
full_row.join('-')
end
# Builds the full rangoli as an array of strings.
def build_rangoli(n)
width = row_pattern(n, n - 1).length
rows = []
# Upper part (including middle)
(0...n).each do |row|
rows << row_pattern(n, row).center(width, '-')
end
# Lower part (mirror of upper, excluding middle)
(n - 2).downto(0) do |row|
rows << row_pattern(n, row).center(width, '-')
end
rows
end
# Prints the rangoli for a given size N.
def print_rangoli(n)
build_rangoli(n).each { |line| puts line }
end
# Run the program with N = 5
print_rangoli(5)
=begin
run:
--------e--------
------e-d-e------
----e-d-c-d-e----
--e-d-c-b-c-d-e--
e-d-c-b-a-b-c-d-e
--e-d-c-b-c-d-e--
----e-d-c-d-e----
------e-d-e------
--------e--------
=end
