Pascal's triangle: Difference between revisions

=={{header|CoffeeScript}}==

This version assumes n is an integer and n >= 1. It efficiently computes binomial coefficients.

<lang coffeescript>

pascal = (n) ->

width = 6

for r in [1..n]

s = ws (width/2) * (n-r) # center row

output = (n) -> s += pad width, n

cell = 1

output cell

# Compute binomial coefficients as you go

# across the row.

for c in [1...r]

cell *= (r-c) / c

output cell

console.log s

ws = (n) ->

s = ''

s += ' ' for i in [0...n]

s

pad = (cnt, n) ->

s = n.toString()

# There is probably a better way to do this.

cnt -= s.length

right = Math.floor(cnt / 2)

left = cnt - right

ws(left) + s + ws(right)

pascal(7)

</lang>

output

<pre>

> coffee pascal.coffee

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

</pre>