I get 580085, why is it wrong? And is there another way to check whether a number is a palindrome?
def reverse(str, aux=''):
count = len(str)
while count > 0:
aux += str[count-1]
count -= 1
return aux
def palindrome(num):
j = str(num)
if j == reverse(j):
return 1
else:
return 0
i = 999
found = 0
while i > 99 and not found:
j = 999
while j > 99 and not found:
if palindrome(i * j):
found = 1
print(i * j)
else:
j -= 1
if not found:
i -= 1
My post is mostly code, but I don't have anything else to say.
Took some time and studied the problem. I tried taking the reversed approach (starting from palindrome numbers, and find their dividers (if any)). Using Py354 on Win10.
code.py:
import time
from math import sqrt
def reverse(str, aux=''):
count = len(str)
while count > 0:
aux += str[count-1]
count -= 1
return aux
def palindrome(num):
j = str(num)
if j == reverse(j):
return 1
else:
return 0
def question_makhfi_0():
ret = 0
i = 999
found = 0
while i > 99 and not found:
j = 999
while j > 99 and not found:
if palindrome(i * j):
found = 1
ret = i * j
else:
j -= 1
if not found:
i -= 1
return ret, i, j
def answer_makhfi_0():
i = 999
_max = 0
while i > 99:
j = 999
while j > 99:
num = i * j
if palindrome(num):
if num > _max:
_max = num
factor0, factor1 = i, j
j -= 1
i -= 1
return _max, factor0, factor1
"""
def answer_makhfi__0_improved_0():
i = j = 999
prod = i * j
step = 0
while prod > 100000:
if step % 2:
i -= 1
else:
j -= 1
prod = i * j
prod_str = str(prod)
if prod_str == prod_str[::-1]:
return prod
step += 1
"""
def answer_cfati_0():
pal = 999999
while pal >= 900009:
if pal % 10 == 9:
pal_str = str(pal)
if pal_str == pal_str[::-1]:
pal_sqrt = sqrt(pal)
for factor0 in range(101, int(pal_sqrt) + 1):
if pal % factor0 == 0:
factor1 = int(pal / factor0)
if 100 <= factor1 <= 999:
return pal, factor0, factor1
pal -= 10
#return pal
def time_func(f, *args):
t0 = time.time()
res = f(*args)
t1 = time.time()
return t1 - t0, res
if __name__ == "__main__":
for func in [question_makhfi_0, answer_makhfi_0, answer_cfati_0]:
print("\nStarting: {}".format(func.__name__))
#print(func.__name__)
res = time_func(func)
print(" Time: {:.6f}\n Result: {}".format(*res))
Notes:
answer_makhfi_0:
max by _max to avoid shadowing builtin namesreturn statement at the end (highly inefficient, anyway)answer_cfati_0:
[900009, 999999] range, that can be expressed as a 2 (3 digit) numbers product. It's fair to assume that (tests support this). However if aiming for bullet proof code, this form won't do it, I'll have to adjust it a bit (it will be a loss performance-wise)Output:
"e\Work\Dev\StackOverflow\q47999634>"e:\Work\Dev\VEnvs\py35x64_test\Scripts\python.exe" code.py Starting: question_makhfi_0 Time: 0.008551 Result: (580085, 995, 583) Starting: answer_makhfi_0 Time: 1.457818 Result: (906609, 993, 913) Starting: answer_cfati_0 Time: 0.012599 Result: (906609, 913, 993)
According to the output, differences between original and new code (for one run, as times vary):
@EDIT0: