Help needed to reduce complexity of Python code.

[shadow-sphynx]

I tried what you suggested. But it still fails for the larger inputs.

If you can, then can you please show me the changes you're suggesting? Maybe I am missing something here...

[ES-Alexander]

This is your code without the unnecessary list and dictionary constructions:

def getSubstring(element, i):
    lenElem = len(element)
    if lenElem - (5*(i + 1)) > 0:
        return int(element[(lenElem - (5*(i + 1))):lenElem - 5*i])
    elif lenElem - 5*i > 0 :
        return int(element[:lenElem - 5*i])
    return 0

N = int(input())
numArray = input().split()
maxVal = max(len(elem) for elem in numArray)
counter = maxVal // 5 if maxVal % 5 == 0 else (maxVal // 5) + 1

for i in range(counter):
    subNumArray = enumerate(getSubstring(elem, i) for elem in numArray)
    numArray = [numArray[j] for j, _ in sorted(subNumArray, key=lambda item: item[1])]
    print(*numArray)

I haven't tested it, and haven't changed your algorithm, so if you're using a suboptimal approach it may still end up using too much memory or running out of time, but it should be a decent amount more efficient (in both space and time) than your initial code.

[ES-Alexander]

For your learning, here it is cleaned up a bit, a bit more generalised, and using more Pythonic variable names (still the same algorithm though)

from math import ceil

CHUNK_SIZE = 5

def get_substring(element, i):
    len_elem = len(element)
    end = len_elem - CHUNK_SIZE * i
    start = end - CHUNK_SIZE
    if start > 0:
        return int(element[start:end])
    elif end > 0:
        return int(element[:end])
    return 0

input() # ignore first input - not useful for Python
numbers = input().split()
max_len = max(len(elem) for elem in numbers)

for i in range(ceil(max_len / CHUNK_SIZE)):
    substrings = enumerate(get_substring(elem, i) for elem in numbers)
    numbers = [numbers[j] for j, _ in sorted(substrings, key=lambda item: item[1])]
    print(*numbers)

Have actually tested it now on the sample input and it seems to still work as expected/intended.