AusPostCode/chicanery.py

#!/usr/bin/env python3
import math
import string

chars = string.digits + string.ascii_letters


def to_base(num, base):
	if base > len(chars):
		raise ValueError(f"Base must be less than {len(chars)}")

	if abs(num) == 0:
		return str(num)
	else:
		negative = num < 0
		num = abs(num)

		digits = []
		while num:
			digits.append(chars[num % base])
			num //= base

		return ('-' if negative else '') + ''.join(digits[::-1])


test_me = {
	"023": "a",
	"030": "b",
	"031": "c",
	"032": "d",
	"033": "e",
	"103": "f",
	"113": "g",
	"123": "h",
	"130": "i",
	"131": "j",
	"132": "k",
	"133": "l",
	"203": "m",
	"213": "n",
	"223": "o",
	"230": "p",
	"231": "q",
	"232": "r",
	"233": "s",
	"303": "t",
	"313": "u",
	"323": "v",
	"330": "w",
	"331": "x",
	"332": "y",
	"333": "z"
}

for i, code in enumerate(test_me.keys()):
	# the lowercase letter codes use a pattern that repeats every seven letters.
	# starting from 030Q (12D), the code increments by one three times, then increments by four four times.

	# firstly, increase the output by 16 for every 7 in the input.
	# then, if i % 7 is 0, 1, 2, or 3, add that number to the output.
	# otherwise, subtract 3 from i % 7, multiply the result by 4, and add that to the output.
	# finally, add 11, because that's where the lowercase chars start.
	out = i // 7 * 16 + max((i % 7 - 3) * 4, i % 7) + 11

	check = int(code, 4)

	print(f"In: {i:03}\tOut: {out:03}\tCode: {to_base(out, 4).zfill(3)} {('GOOD' if check == out else 'FAIL')}")

print("\n===================\n")

for i, code in enumerate(test_me.keys()):
	# now to do the process in reverse - converting a letter code to an index.
	# first we subtract 11 to get the codes to start from zero.
	x = int(code, 4) - 11

	# first, add 7 for every 16 in the input.
	# next, we can use (x + 10) % 16 to get the sequence '10, 11, 12, 13, 14, 2, 6'.
	# we can use min() to replace the 2 with a 5, and then mod the whole sequence by 10 to get 0 through 6 repeating.
	# now we just need to add the two together.
	out = x // 16 * 7 + (max((x + 10) % 16, 5) % 10)

	character = string.ascii_lowercase[out] if out < len(string.ascii_lowercase) else '?'

	print(f"In: {x:03}\tOut: {out:03}\tGoal: {i:03}\tChar: {character} {('GOOD' if character == test_me[code] else 'FAIL')}")

exit(0)

headings = {
	"QUAD": "₄",
	"SEPT": "₇",
	"GOAL7": "₇",
	"DEC": "₁₀",
	"GOAL": "₁₀",
	"ORIG": "₁₀",
	"SXTNS": "₁₀",
	"FOURS": "₁₀",
	"MOD16": "₁₀",
	"MOD7": "₇",
	"MOD8": "₈",
	"MOD4": "₄",
	"MAGIC": ""
}

out = ""
for heading in headings:
	out += f"{heading:8}"
print(out)
print("=" * 8 * len(headings))

goal = 2
successes = 0
for key in test_me.keys():
	# breaks on i in [31, 46, 47, 51, 61, 62, 63]
	#
	original_value = int(key, 4)

	# the code starts at 023₄, which is 11₁₀, so we subtract 11₁₀ as an initial offset
	x = original_value - 1

	sixteens = (x // 16)
	eights = (x // 8)
	mod_sixteen = x % 16
	mod_eight = x % 8
	fours = (x // 4)
	mod_sixteen_mod_seven = mod_sixteen % 7
	# magic = abs(-8 + ((mod_eight // mod_sixteen) * (16 * sixteens + 8 + sixteens)))
	magic = 8

	letter_index = ((7 * sixteens) + (x % 8)) - ((1 - (mod_sixteen // 8)) * (2 + 3 * (fours % 2)))

	output = [
		key,
		to_base(letter_index, 7),
		to_base(goal, 7),
		letter_index,
		goal,
		x,
		sixteens,
		fours,
		mod_sixteen,
		mod_sixteen_mod_seven,
		mod_eight,
		x % 4,
		magic
	]

	colour_code = 91
	if goal == letter_index:
		successes += 1
		colour_code = 0

	print(f'\033[{colour_code}m', end='')

	out = ""
	for i, suffix in enumerate(headings.values()):
		value = str(output[i]).zfill(3) + suffix
		out += f"{value:8}"

	print(out)

	goal += 1

print(f"Succeeded on {successes} of {goal} attempts ({math.floor(successes / float(goal) * 100)}%)")

exit(0)

outputs = {
	"decimals": [],
	"indices": [],
	"mod_fours": [],
	"divided_by_sixteens": [],
	"indices_plus_mod_fours": [],
	"actual_indices": [],
	"correctness_checks": []
}

position = 0

for x, expected_value in test_me.items():
	wacky = " [WACKY]" if x[1] != "3" else ""
	num = int(x, 4) - 11
	index = (num // 4)
	mod_four = num % 4
	divided_by_sixteen = ((num) // 16)
	# actual_index = index + mod_four + (3 * divided_by_sixteen)
	actual_index = (num // 4) + (num % 4) + (3 * ((num - 4) // 16)) + 3
	# actual_index = (num // 16) * 7 + (num % 4)

	correctness_check = "GUD" if actual_index == position else "OOP"

	outputs["decimals"].append(f"{num:3d}")
	outputs["indices"].append(f"{index:3d}")
	outputs["mod_fours"].append(f"{mod_four:3d}")
	outputs["divided_by_sixteens"].append(f"{divided_by_sixteen:3d}")
	outputs["indices_plus_mod_fours"].append(f"{mod_four + index:3d}")
	outputs["actual_indices"].append(f"{actual_index:3d}")
	outputs["correctness_checks"].append(correctness_check)

	position += 1

# print(f"{i}Q = {num}D{wacky}: {index}")

print(' '.join(test_me.keys()))
print('  ' + '   '.join(test_me.values()))

# ignored_outputs = [""]
for key, numbers in outputs.items():
	print(' '.join(numbers) + f" ({key})")