11-liner: simple clear solution for 15-puzzle Solvability by przemyslaw.daniel - python coding challenges

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11-liner: simple solution in Clear category for 15-puzzle Solvability by przemyslaw.daniel

from itertools import combinations


def fifteen_puzzle(tiles: list[list[int]], blank: int = 16) -> bool:
    
    tiles = sum(tiles, [])
    row = tiles.index(blank) // 4 + 1
    tiles.remove(blank)
    inversions = sum(x > y for x, y in combinations(tiles, r=2))

    return not (inversions + row) % 2

March 26, 2023

Comments:

CDG.Axel on March 27, 2023, 5:20 p.m.
For detailed review

CDG.Axel on March 27, 2023, 5:25 p.m.
Thanks for remembering sum(iterable, start). I forgot it again and wrote this: <pre class='brush: python'>tiles = [e for line in tiles for e in line] </pre>

CDG.Axel on March 27, 2023, 9:10 p.m.
Btw you can avoid 'tiles.remove' by changing comprehension <pre class='brush: python'>tiles = sum(tiles, []) row = tiles.index(blank) // 4 + 1 inversions = sum(blank > x > y for x, y in combinations(tiles, r=2)) return not (inversions + row) % 2 </pre>

przemyslaw.daniel on March 28, 2023, 11:35 a.m.
I left blank tile configurable (blank: int = 16) so maybe it's better to not use the condition. But in this particular case your proposal will also work

CDG.Axel on March 28, 2023, 5:04 p.m.
Ok, I saved one symbol ('>' instead of '!='). It looks like next code remains configurable for any blank :) <pre class='brush: python'>sum(blank != x > y for x, y in combinations(tiles, r=2)) </pre>

StefanPochmann on March 28, 2023, 11:58 p.m.
Lol, advertizing as "11-liner" and counting four empty lines. You're weird :-)

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