Offline real-time how to write Python implementation example of E15 problem

Problem: http://nabetani.sakura.ne.jp/hena/orde15nohil/ Answer links: http://qiita.com/Nabetani/items/705fa83cfbf20377b92f Event: https://yhpg.doorkeeper.jp/events/61418

1. Set "Number" to "3rd digit" and create a digit string for each number range that makes up a set of NxN blocks.
2. In order to convert the "number" to "x, y coordinates" with 2x2 as the minimum unit, adjust each digit of the ternary number to 0 or 1 to make it "binary".
3. Find the adjacent "number" from each of the four adjacent "x, y coordinates" on the top, bottom, left, and right.
4. To find the "number", adjust each digit of the "binary number" of the "x, y coordinates" to 0, 1, 2 to make it a "ternary number".
5. However, the "x, y coordinates" corresponding to the blank in the lower right do not become the "number".

#!/usr/bin/env python
# -*- coding:utf-8 -*-

def base(n, b):
    return (n // b and base(n // b, b) or '') + str(n % b)

def number(x, y):
    return (x < 0 or y < 0 or x & y != 0 or  # return True if there is no number
            int(str(int(bin(x)[2:]) + int(bin(y)[2:].replace('1', '2'))), 3))  # x:0or1 + y:0or2

def solve(data):
    digits = base(int(data), 3)
    x = int(digits.replace('2', '0'), 2)                    # x:012 -> 010
    y = int(digits.replace('1', '0').replace('2', '1'), 2)  # y:012 -> 001
    neighbors = number(x, y - 1), number(x - 1, y), number(x + 1, y), number(x, y + 1)
    return ','.join(str(n) for n in neighbors if n is not True)

def test(n, data, correct):
    answer = solve(data)
    if answer == correct:
        print('OK #%s: "%s" -> "%s"' % (n, data, answer))
    else:
        print('NG #%s: "%s" -> "%s" != "%s"' % (n, data, answer, correct))

test(0, "21", "19,22,23")
test(1, "0", "1,2")
test(2, "1", "0,3")
test(3, "2", "0,6")
test(4, "3", "1,4,5")
test(5, "4", "3,9")
test(6, "9", "4,10,11")
test(7, "15", "11,16,17")
test(8, "27", "13,28,29")
test(9, "32", "30")
test(10, "47", "45,51")
test(11, "65", "63,69")
test(12, "80", "78,162")
test(13, "199", "198,201")
test(14, "204", "200,205,206")
test(15, "243", "121,244,245")
test(16, "493", "492")
test(17, "508", "507")
test(18, "728", "726,1458")
test(19, "793", "792,795")
test(20, "902", "900,906")
test(21, "981", "976,982,983")
test(22, "1093", "1092,2187")
test(23, "1202", "1200")
test(24, "1300", "1299,1305")
test(25, "1962", "1952,1963,1964")
test(26, "2188", "2187,2190")
test(27, "2405", "2403,2409")
test(28, "3326", "3324")
test(29, "6561", "3280,6562,6563")
test(30, "6612", "6608,6613,6614")
test(31, "7058", "7056,7062")
test(32, "8444", "8442,8448")
test(33, "9841", "9840,19683")
test(34, "15243", "15239,15244,15245")
test(35, "19946", "19944,19950")
test(36, "21148", "21147")
test(37, "39365", "39363")
test(38, "39366", "19682,39367,39368")
test(39, "55694", "55692,55698")
test(40, "57245", "57243")
test(41, "66430", "66429,66432")
test(42, "92740", "92739")
test(43, "115250", "115248")
test(44, "163031", "163029")
test(45, "221143", "221142,221157")
test(46, "410353", "410352")
test(47, "412649", "412647,412659")
test(48, "550391", "550389")
test(49, "699921", "699880,699922,699923")
test(50, "797161", "797160,1594323")
test(51, "1000000", "999999,1000002")