Day 11

Author: davidaugustat

day11/day11.py

@@ -0,0 +1,84 @@
+def find_empty_rows_and_columns(image):
+ r = len(image)
+ c = len(image[0])
+
+ # find empty rows and columns:
+ row_is_empty = [True for _ in range(r)]
+ col_is_empty = [True for _ in range(c)]
+ for i in range(r):
+ for j in range(c):
+ if image[i][j] != '.':
+ row_is_empty[i] = False
+ col_is_empty[j] = False
+ 
+ empty_rows = [i for i in range(r) if row_is_empty[i]]
+ empty_columns = [i for i in range(c) if col_is_empty[i]]
+ return empty_rows, empty_columns
+
+
+def expand_galaxies(galaxies, empty_rows, empty_cols, expansion_factor=1000000):
+ # shift by row:
+ for row in empty_rows[::-1]:
+ for i in range(len(galaxies)):
+ if galaxies[i][0] > row:
+ galaxies[i] = (galaxies[i][0] + expansion_factor-1, galaxies[i][1])
+
+ # shift by column:
+ for col in empty_cols[::-1]:
+ for i in range(len(galaxies)):
+ if galaxies[i][1] > col:
+ galaxies[i] = (galaxies[i][0], galaxies[i][1] + expansion_factor-1)
+
+ return galaxies 
+
+
+def find_galaxy_positions(image):
+ galaxies = []
+ r = len(image)
+ c = len(image[0])
+ for i in range(r):
+ for j in range(c):
+ if image[i][j] == '#':
+ galaxies.append((i,j))
+ return galaxies
+
+
+def get_distance(galaxy1, galaxy2):
+ return abs(galaxy1[0] - galaxy2[0]) + abs(galaxy1[1] - galaxy2[1])
+
+
+def find_distances_sum(galaxies):
+ sum = 0
+ for i in range(len(galaxies)):
+ for j in range(i+1, len(galaxies)):
+ distance = get_distance(galaxies[i], galaxies[j])
+ sum += distance
+ return sum
+
+
+def print_image(image):
+ for r in image:
+ print(''.join(r))
+
+
+def expand_and_find_distance_sum(image, expansion_factor):
+ galaxies = find_galaxy_positions(image)
+ empty_rows, empty_cols = find_empty_rows_and_columns(image)
+ expand_galaxies(galaxies, empty_rows, empty_cols, expansion_factor)
+ return find_distances_sum(galaxies)
+
+
+def read_data_from_file(filename):
+ with open(filename) as file:
+ image = [[c for c in line.rstrip()] for line in file]
+ return image
+
+
+image = read_data_from_file("input.txt")
+# image = read_data_from_file("testinput.txt")
+
+# part1_result = expand_and_find_distance_sum(image, 2)
+# print("Part 1:", part1_result)
+
+part2_result = expand_and_find_distance_sum(image, 1000000)
+print("Part 2:", part2_result)