day4.py

# --- Day 4: Secure Container ---
# You arrive at the Venus fuel depot only to discover it's protected by a password. The Elves had written the password on a sticky note, but someone threw it out.

# However, they do remember a few key facts about the password:

# It is a six-digit number.
# The value is within the range given in your puzzle input.
# Two adjacent digits are the same (like 22 in 122345).
# Going from left to right, the digits never decrease; they only ever increase or stay the same (like 111123 or 135679).
# Other than the range rule, the following are true:

# 111111 meets these criteria (double 11, never decreases).
# 223450 does not meet these criteria (decreasing pair of digits 50).
# 123789 does not meet these criteria (no double).
# How many different passwords within the range given in your puzzle input meet these criteria?

# --- Part Two ---
# An Elf just remembered one more important detail: the two adjacent matching digits are not part of a larger group of matching digits.

# Given this additional criterion, but still ignoring the range rule, the following are now true:

# 112233 meets these criteria because the digits never decrease and all repeated digits are exactly two digits long.
# 123444 no longer meets the criteria (the repeated 44 is part of a larger group of 444).
# 111122 meets the criteria (even though 1 is repeated more than twice, it still contains a double 22).
# How many different passwords within the range given in your puzzle input meet all of the criteria?

puzzle_input = [231832, 767346]
meet_crit = 0
for number in range(233333, 700000):
    pwd = list(str(number))
    prev_prev = 0
    previous = int(pwd[0])
    increases = True
    double = dict()  # digit: boolean
    for num in pwd[1:]:
        n = int(num)
        if n < previous:
            increases = False
            break
        # part two different from part one here
        # part one is without prev_prev
        double[n] = n == previous and n != prev_prev
        prev_prev, previous = previous, n
    if increases:
        for digit in double:
            if double[digit]:
                meet_crit += 1
                break
    
print("Valid pwds:", meet_crit)