Advent of Code 2023 Day 9

— Day 9: Mirage Maintenance —

Oasis And Sand Instability Sensor

Analyze your OASIS report and extrapolate the next value for each history. What is the sum of these extrapolated values?

with open('data-2023-09.txt', 'r') as f:
    inp = f.read().splitlines()

Looooops

oasis = [list(map(int, x.split())) for x in inp]

summer = 0

# go through the list
for o in oasis: 
    # print(o)
    # collect some other lists, until we reach zeros
    cll = []
    # the first list in our collection is the original list
    cll.append(o)
    # loop through while we don't have zeros
    while not all([x == 0 for x in cll[-1]]):
        # create a new list of differences
        dd = [q - p for p,q in zip(cll[-1], cll[-1][1:])]
        # add it in 
        cll.append(dd)
        # print(dd)

    # let's go back through this list, I think
    # add the previous number from one list to the next
    u = 0
    for r in cll[::-1]:
        u += r[-1]
    # keep track of everything
    # print(u)
    summer += u
        
summer    

# 1721780360
# 1782868781

1782868781

— Part Two —

Analyze your OASIS report again, this time extrapolating the previous value for each history. What is the sum of these extrapolated values?

This took about two minutes! Sometimes you stumble on something nice.

oasis = [list(map(int, x.split())) for x in inp]

summer = 0

# go through the list
for o in oasis: 
    # print(o)
    # collect some other lists, until we reach zeros
    cll = []
    # the first list in our collection is the original list
    cll.append(o)
    # loop through while we don't have zeros
    while not all([x == 0 for x in cll[-1]]):
        # create a new list of differences
        dd = [q - p for p,q in zip(cll[-1], cll[-1][1:])]
        # add it in 
        cll.append(dd)
        # print(dd)

    # let's go back through this list, I think
    # add the previous number from one list to the next
    u = 0
    for r in cll[::-1]:
        u = r[0] - u
        # print(u)
    # keep track of everything
    # print(u)
    summer += u
        
summer    

# 1057

1057