ProjectEuler#4 Largest palindrome product

#A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers #is 9009 = 91 × 99.

#Find the largest palindrome made from the product of two 3-digit numbers.

#isPal algorithm from MIT 6.00x course notes

#Analysis
#A brutish way to find the largest palindrome product of two 3-digit numbers is by searching odd factors downwards #from 999. We test each product as a palindrome and save it. Our search ends when the next product falls below the #largest palindrome found.
#The two factors are printed along with their product.

def isPal(s):
    if len(s) <= 1:
        return True
    else:
        return s[0] == s[-1] and isPal(s[1:-1])


pmax = 0
for i in range(999,100,-2):
  for j in range(i,100,-2):
    p = i*j
    if p < pmax: break
    if isPal(p): x,y,pmax = i,j,p

print x,'x',y,'=',pmax