Regex FTW! clear solution for Count And Say by H0r4c3 - python coding challenges

Enable Javascript in your browser and then refresh this page, for a much enhanced experience.

Regex FTW! solution in Clear category for Count And Say by H0r4c3

import re

def count_and_say(digits: str) -> str:
    result = ''
    
    pattern = r'(.)\1*'
    digits_found = re.finditer(pattern, digits)
   
    for groups in digits_found:
        result += str(len(groups.group())) + groups.group()[0]
    
    return result


print("Example:")
print(count_and_say("123"))

# These "asserts" are used for self-checking
assert count_and_say("333388822211177") == "4338323127"
assert count_and_say("1") == "11"
assert count_and_say("") == ""

print("The mission is done! Click 'Check Solution' to earn rewards!")

Feb. 25, 2024

Comments:

kdim on March 24, 2024, 3:13 p.m.
Good use of RE. Why didn't you use ''.join()?

H0r4c3 on March 24, 2024, 3:23 p.m.
You're right! .join() would have been more pythonic.

StefanPochmann on March 25, 2024, 12:29 a.m.
But with <pre class='brush: python'>finditer</pre> and <pre class='brush: python'>+=</pre>, you're using much less memory than any <pre class='brush: python'>join</pre> solution, so that's an advantage. Measured with tracemalloc for a long string: <pre class='brush: python'> 1.00 MB count_and_say 26.67 MB count_and_say_2 30.83 MB count_and_say_3 </pre> <pre class='brush: python'>count_and_say_2</pre> just uses <pre class='brush: python'>join</pre> instead of <pre class='brush: python'>+=</pre>, and <pre class='brush: python'>count_and_say_3</pre> additionally uses <pre class='brush: python'>findall</pre> instead of <pre class='brush: python'>finditer</pre>. Code: <pre class='brush: python'>import tracemalloc as tm import re def count_and_say(digits: str) -> str: result = '' pattern = r'(.)\1*' digits_found = re.finditer(pattern, digits) for groups in digits_found: result += str(len(groups.group())) + groups.group()[0] return result def count_and_say_2(digits: str) -> str: pattern = r'(.)\1*' digits_found = re.finditer(pattern, digits) return ''.join([ str(len(groups.group())) + groups.group()[0] for groups in digits_found ]) def count_and_say_3(digits: str) -> str: pattern = r'(.)\1*' digits_found = re.findall(pattern, digits) return ''.join([ str(len(group)) + group[0] for group in digits_found ]) funcs = count_and_say, count_and_say_2, count_and_say_3 digits = '333388822211177' for f in funcs: print(count_and_say(digits)) digits *= 10**5 for f in funcs: tm.start() f(digits) print(f'{tm.get_traced_memory()[1] / 1e6 :5.2f} MB ', f.__name__) tm.stop() </pre> <a href="https://ato.pxeger.com/run?1=rZO9TsMwEMcHtjzFbbb7EZpUpVGlMrDzBKWyosQuQYkdOZehQjwJSxd4KGYeBCcx9EMpEqJeLJ_P_7vf-e71vdzio1a73VuNchx9XH1mRakNApo4EUWc5zqBuAIsPHdhhOelQkKia4U8Vimv4i1Ns02G1QIqNAzGt82-8MAuI6o6R1gCIe25jBGFUdZgCPXZQzDo7J0Al1Y1bS6FLzOVZtaXuicj58Naf6kNbIyuywoydfS6i3sQe7hs0qG5ULR74bcbZYzBEI5Nq8napY21zbJT6AHm4XnkSyG6HAjxn3Sm6OqH6880vxesdVmzPsrppShtI_0Hcs_Wi3SWSNYqqWwWR1Sj0688NUxtKVq1pm2ndkVRFIZhEATzOfGaqLKJ2Iq7YphMIe0bCcZ-xAZLCCaDwczrlcDCrzA2SF1_08MqdfqSPFuvjUDeTmfKC1Fos7X_HKzhGgJxA4uZH8oXuL8DMgLpc67iQnDO9iG07Ytu2N3Mf8_-Fw">Attempt This Online!</a>

StefanPochmann on March 25, 2024, 1:11 a.m.
But with <pre class='brush: python'>finditer</pre> and <pre class='brush: python'>+=</pre>, you’re using very little memory, much less memory than <pre class='brush: python'>join</pre> would. Measured with tracemalloc for a long string: <pre class='brush: python'> 1.00 MB count_and_say 26.67 MB count_and_say_join </pre> Code: <pre class='brush: python'>import tracemalloc as tm import re def count_and_say(digits: str) -> str: result = '' pattern = r'(.)\1*' digits_found = re.finditer(pattern, digits) for groups in digits_found: result += str(len(groups.group())) + groups.group()[0] return result def count_and_say_join(digits: str) -> str: pattern = r'(.)\1*' digits_found = re.finditer(pattern, digits) return ''.join([ str(len(groups.group())) + groups.group()[0] for groups in digits_found ]) funcs = count_and_say, count_and_say_join digits = '333388822211177' for f in funcs: print(f(digits)) digits *= 10**5 for f in funcs: tm.start() f(digits) print(f'{tm.get_traced_memory()[1] / 1e6 :5.2f} MB ', f.__name__) tm.stop() </pre> <a href="https://ato.pxeger.com/run?1=rVNLTsMwEJVY-hSzi91PaIJKo0plwZ4TlMqyErsYJXbkTBYV4iRsuoFDcRU2OIkprVSQkPDG8njmvXnPnpe3eocP1uz3ry2qafZ-8aGr2joEdCKXlShLm4NoACsSLpwkpJAKctsa5MIUvBE7WuitxmYJDToG05tuXxLwy8mmLRFWEEX9uRaI0hkfcBGN2X0yGuIDAFceteguZay0KbTPpaFkEnJYn6-sg62zbd2ANifVA-8R93jVtUNLaehQEfcbZYzBGE5D69kmtI2t73JAOCOYP1ptflb9XypDG1EU93zrg7Q_C_rdsz5lwwhRrckb39mJ2MkZ7d6Tvr572Su_sixL0zRJksUiIh2R6jh6uGCJ0wapCp4xdgAYrSCZjUZzcrYMq7hB4ZCGZ6fH9gTM6MlnbSXy_tMWvJKVdTuvPdnAJSTyGpbzOFXPcHcL0QRUzLkRleScfVNY79UwA2EUvkbiEw">Attempt This Online!</a>

Ice Base

0 %

PyCharm The Python IDE for Professional Developers. Enjoy productive Python, web and scientific development with PyCharm. Download it now!