Re: The "Strand" puzzle --- ( Continued Fractions using Lisp or Python? )

ilan_no_spew@hotmail.com (IlanMayer) writes:

On Mon, 29 Jul 2024 18:58:21 +0000, HenHanna wrote:

On 7/26/2024 5:37 AM, IlanMayer wrote:

   So the solutions to the Strand puzzle can be found from the
continued fraction of \sqrt{2}, which  _is_  satisfying simple.
  Using Mathematica to look at the first 10 convergents

>
---------- is this (also) easy to do using Lisp or Python???

>
This can be done with Python:
>
N = 10
a = 1
b = 1
print(str(a) + "/" + str(b))
for n in range(N):
   temp = a + 2 * b
   b = a + b
   a = temp
   print(str(a) + "/" + str(b))

Let's play golf!

There's no need for temp:

b = b + a
a = 2 * b - a

Pre:
$ perl -e '$a=1;$b=1;$n=0;while($n++<10){print("$a/$b\n");$t=$a+2*$b;$b=$a+$b;$a=$t;}'
1/1
3/2
7/5
17/12
41/29
99/70
239/169
577/408
1393/985
3363/2378

Post:
$ perl -e '$a=1;$b=1;$n=0;while($n++<10){print("$a/$b\n");$b+=$a;$a=2*$b-$a;}'
1/1
3/2
7/5
17/12
41/29
99/70
239/169
577/408
1393/985
3363/2378

Phil
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