The figure is the union of unit squares, there aren't triangles.

Imagine a plane divided in unit squares, each square has (x,y) coordinates.

Added an image with examples in description.

@jacosta66, if you're asking about what O(n) means (or the "O(...)" notation in general is), its basically a way to estimate what the upper bound of execution time a certain piece of code would take to complete.

An example of O(n) means that a function will complete in the worst case by parsing a given list a constant number of times. So with a list of 100 elements, we can expect the upper time complexity limit to be a multiple of the time it takes to process all 100 elements.

Conversely, O(n^2) means that for every element in the list, we have to parse the entire rest of the list elements. So for 100 elements, we can parse somewhere around 100^2 or 10000 elements total. That difference in time taken is what makes the 10 million element case impossible to solve within a reasonable timeframe.

I'm afraid there is no link as you wanted, just think simple, code simple. Other authors and I just use basic datatypes to solve this one

you passed the simple test, not ALL
NOTE: There will also be lists tested of lengths upwards of 10,000,000 elements. Be sure your code doesn't time out.
this kata requires O(n) solution, try to use a better way.
Hint for python guys, if you are already use for each, don't use operator "in" or "not in" inside
good luck

i have the same conclusion, and i dont know how to fix it
i have 2 "for ..." in my code, but i've used time library for python and it is OK
i'm from russia, sorry if i have mistakes

'1go litt2le pa3rt that4 5in 6case ' # your returned string has a trailing space
'1go litt2le pa3rt that4 5in 6case'  # the expected value hasn't

Read this: https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution