Life & Research Notes

My solution to the Pascal’s Triangle quiz this week:

#!/usr/bin/env ruby

def center_str s, len
  n = (len - s.length) / 2.0
  ' '*(n.floor) + s + ' '*(n.ceil)
end

n = ARGV[0].to_i
rows = [[1]]
for i in 1..(n-1)
  k = -1; r = rows[i-1] + [0]
  rows << r.map{ |x| j = k; k+=1; x + r[j] }
end
m = rows.last[n/2].to_s.length * 2
n = n * m
rows.each do |r|
  puts center_str(r.collect{|x| center_str(x.to_s, m)}.join, n)
end

Sample output:

                             1
                          1     1
                       1     2     1
                    1     3     3     1
                 1     4     6     4     1
              1     5     10    10    5     1
           1     6     15    20    15    6     1
        1     7     21    35    35    21    7     1
     1     8     28    56    70    56    28    8     1
  1     9     36    84   126   126    84    36    9     1

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