How to improve performance of this code?

Question

Thanks to some help from people here, I was able to get my code for Tasmanian camels puzzle working. However, it is horribly slow (I think. I\'m not sure because this is my

Answer 1

My other answer is rather long, so I decided to list this as a separate answer. This problem is really better suited to doing a depth-first search. I made a depth-first search solution and it is much, much faster than the optimized A-star method made with the changes outlined in my other answer (which is much, much faster than the OP code). For instance, here are the results for running both my A-star and my depth-first search methods on the 17 camels per side case.

A-star:  14.76 seconds
Depth-first search: 1.30 seconds

Here's my depth-first method code if you are interested:

from sys import argv

fCamel = 'F'
bCamel = 'B'
gap = 'G'

def issolution(formlen):
    def solution(formation):
        if formation[formlen2] == gap:
            return formation.index(fCamel) == x
        return 0
    x = formlen/2 + 1
    formlen2 = formlen/2
    return solution

def solve(formation):
    def depthfirst(form, g):
        if checksolution(form):
            return [tuple(form)], g + 1
        else:
            igap = form.index(gap)
            if(igap > 1 and form[igap-2] == fCamel):
                form[igap-2],form[igap] = form[igap],form[igap-2]
                res = depthfirst(form,g+1)
                form[igap-2],form[igap] = form[igap],form[igap-2]
                if res != 0:
                    return [tuple(form)]+res[0],res[1]
            if (igap < flen - 2) and form[igap + 2] == bCamel:
                form[igap+2],form[igap] = form[igap],form[igap+2]
                res = depthfirst(form,g+1)
                form[igap+2],form[igap] = form[igap],form[igap+2]
                if res != 0:
                    return [tuple(form)]+res[0],res[1]
            if(igap > 0 and form[igap-1] == fCamel):                
                form[igap-1],form[igap] = form[igap],form[igap-1]
                res = depthfirst(form,g+1)
                form[igap-1],form[igap] = form[igap],form[igap-1]
                if res != 0:
                    return [tuple(form)]+res[0],res[1]               
            if (igap < flen - 1) and form[igap+1] == bCamel:
                form[igap+1],form[igap] = form[igap],form[igap+1]
                res = depthfirst(form,g+1)
                form[igap+1],form[igap] = form[igap],form[igap+1]
                if res != 0:
                    return [tuple(form)]+res[0],res[1]                
            return 0
    flen = len(formation)
    checksolution = issolution(flen)
    res = depthfirst(list(formation), 0)
    return res

L = lambda x: tuple([fCamel]*x + [gap] + [bCamel]*x)
print solve(L(int(argv[1])))