Advent of Code 2022 Day 25

— Day 25: Full of Hot Air —

You have to figure out the fuel requirements for some hot air balloons. There is some funky base-5 math going on

The Elves are starting to get cold. What SNAFU number do you supply to Bob’s console?

with open('data-2022-25.txt', 'r') as f:
    inp = f.read().splitlines()

Weird base five arithmetic, but not really a different base because there are negatives.

d5 = {'2': 2, 
      '1': 1, 
      '0': 0, 
      '-': -1, 
      '=': -2,
      }

max(inp, key=len)

len(max(inp, key=len))

nums = []

for i in inp:
    s = 0
    for e,j in enumerate(reversed(i)): 
        # print(j, e)
        s += d5[j] * (5 ** e)
    nums.append(s)
 
sum(nums)

34279402189875

Now to reverse engineer the special encoded number

z = sum(nums)
y = ''
# z / (5 ** 19)
# z - 2 * 5**19

d5 = {2: '2', 
      1: '1', 
      0: '0', 
      -1: '-', 
      -2: '=',
      }

for x in range(19, -1, -1):
    # print(x)
    # print(z)
    w = 5 ** x
    v = z / w
    # print(v)
    if abs(v) > 0.5:
        u = round(v)
        y += d5[u]
        z -= u * 5 ** x
    else: 
        y += str(0)
    print(y)

y

2
2-
2-0
2-00
2-00=
2-00=1
2-00=12
2-00=12=
2-00=12=2
2-00=12=21
2-00=12=21-
2-00=12=21-0
2-00=12=21-0=
2-00=12=21-0=0
2-00=12=21-0=01
2-00=12=21-0=01-
2-00=12=21-0=01--
2-00=12=21-0=01--0
2-00=12=21-0=01--00
2-00=12=21-0=01--000

'2-00=12=21-0=01--000'