/r/dailyprogrammer #145 - easy

145e.coffee

#!/usr/bin/env coffee
#
# http://redd.it/1t0r09 -/r/dailyprogrammer
# [12/16/13] Challenge #145 [Easy] Tree Generation


zipWith = (xss..., f) ->
  for i in [0..-1+Math.min.apply 0, (x.length for x in xss)]
    f.apply @, (xs[i] for xs in xss)

mul = (x, n) -> x for _ in [0...Math.max n, 0]

tree = (n, tr='=', le='*', sp=' ') ->
  zipWith \
    (mul sp, (n-i-2)         for i in [0...n]),
    (mul le, (2*i+1)%(2*n-1) for i in [0...n]),
    (mul sp, (n-i-2)         for i in [0...n]),
    (mul [], n-1).concat([(mul sp, n-3).concat (mul tr, 3), (mul sp, n-3)]),
    ((xs, yss...) -> xs.concat.apply xs, yss)


for i in [3..7] by 2
  console.log ((tree i).map (xs) -> xs.join '').join '\n'


# Output:
#  *
# ***
# ===
#    *
#   ***
#  *****
# *******
#   ===
#      *
#     ***
#    *****
#   *******
#  *********
# ***********
#     ===
#