2023 - Day 11 part 2

2023/11/11_2.py

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+#!/usr/bin/env python
+# 2023 - Advent Of Code 11 - part 2
+
+# file = 'input_example.txt'
+file = 'input.txt'
+EXPANSION = 1000000
+
+# pylint: disable=consider-using-with
+input_lines = [line.strip('\n') for line in open(file, encoding="utf-8")]
+print(f'map: ({len(input_lines[0])}, {len(input_lines)})')
+
+stars = []
+for y, _ in enumerate(input_lines):
+    for x in range(0, len(_)):
+        # pylint: disable=unnecessary-list-index-lookup
+        if input_lines[y][x] == '#':
+            stars.append((x, y))
+print(f'stars: {len(stars)}, map: ({len(input_lines[0])}, {len(input_lines)})')
+
+# find empty lines
+empty_lines = []
+for y, _ in enumerate(input_lines):
+    if '#' not in input_lines[y]:
+        empty_lines.append(y)
+print(f'empty lines: {empty_lines}')
+
+# find empty columns
+empty_columns = []
+for x in range(0, len(input_lines[0])):
+    empty = True
+    for y, _ in enumerate(input_lines):
+        if input_lines[y][x] == '#':
+            empty = False
+            break
+    if empty:
+        empty_columns.append(x)
+print(f'empty columns: {empty_columns}')
+
+paths = []
+for s1 in stars:
+    for s2 in stars:
+        if s1 != s2 and {s1, s2} not in paths:
+            paths.append({s1, s2})
+print(f'number of paths: {len(paths)}')
+
+
+# instead of extending the map, offset star coordinates
+def expand_coord(num, compare_list):
+    i = 0
+    for i, star in enumerate(compare_list):
+        if num < star:
+            return i * (EXPANSION-1) + num
+    return (i+1) * (EXPANSION-1) + num
+
+
+# dist = math.abs(x2-x1) + math.abs(y2-y1)
+sum_path = 0
+for path in paths:
+    p = list(path)
+    x1 = expand_coord(p[0][0], empty_columns)
+    x2 = expand_coord(p[1][0], empty_columns)
+    y1 = expand_coord(p[0][1], empty_lines)
+    y2 = expand_coord(p[1][1], empty_lines)
+    dist = abs(x1 - x2) + abs(y1 - y2)
+    sum_path += dist
+    print(f'{path} dist: {dist}')
+
+print(f'{sum_path=}')