AdventOfCode2025.Day04.py

AdventOfCode2025.Day04.py

import pyperclip

input = pyperclip.paste().splitlines()

# Part One

grid = {}
for r in range(len(input)):
    for c in range(len(input[r])):
        grid[(int(r),int(c))] = input[r][c]

def count_neigbors(r, c):
    deltas = [(-1, -1), (-1, 0), (-1, 1),
              (0, -1),          (0, 1),
              (1, -1),  (1, 0), (1, 1)]
    count = 0
    for dr, dc in deltas:
        nr, nc = r + dr, c + dc
        if (nr, nc) in grid and grid[(nr, nc)] == '@':
            count += 1
    return count

count = 0
for r in range(len(input)):
    for c in range(len(input[r])):
        if grid[(r, c)] == '@':
            n = count_neigbors(r, c)
            if n < 4: 
                count += 1

print("Part One:", count)

def remove_accessible():
    counted = []
    count = 0
    for r in range(len(input)):
        for c in range(len(input[r])):
            if grid[(r, c)] == '@':
                n = count_neigbors(r, c)
                if n < 4: 
                    count += 1
                    counted.append((r, c))
    for r, c in counted:
        grid[(r, c)] = '.'
    return count

removed = -1
count = 0
while removed != 0:
    removed = remove_accessible()
    count += removed
print("Part Two:", count)