README.md

@@ -18,3 +18,8 @@
 ### running-with-bunnies
 * Completed in: 1 day, 4 hrs, 40 mins, 40 secs.
 * Shortest Paths
+
+## Level4
+### escape-pods
+* Completed in: 1 day, 2 hrs, 16 mins, 11 secs.
+* Minimum cut

level4/escape-pods/solution.py

@@ -0,0 +1,31 @@
+import numpy as np
+
+def solution(entrances, exits, path):
+    p = np.array(path)
+    minimum_width = -1
+    all_rooms = set(range(len(p)))
+    for rooms, others in generate_rooms(all_rooms, set(entrances), set(exits), p):
+        width = calculate_cut_width(rooms, others, p)
+        if width < minimum_width or minimum_width == -1:
+            minimum_width = width
+    return minimum_width
+
+def generate_rooms(all_rooms, prev_rooms, exits, path):
+    yield prev_rooms, all_rooms - set(prev_rooms)
+    for room, width in enumerate(sum(path[list(prev_rooms)])):
+        if room not in prev_rooms and room not in exits and width != 0:
+            next_rooms = prev_rooms | set([room])
+            for result in generate_rooms(all_rooms, next_rooms, exits, path):
+                yield result
+
+def calculate_cut_width(rooms, others, p):
+    return np.sum(p[list(rooms)][:, list(others)])
+
+tests = [
+        [[[0], [3], [[0, 7, 0, 0], [0, 0, 6, 0], [0, 0, 0, 8], [9, 0, 0, 0]]], 6],
+        [[[0, 1], [4, 5], [[0, 0, 4, 6, 0, 0], [0, 0, 5, 2, 0, 0], [0, 0, 0, 0, 4, 4], [0, 0, 0, 0, 6, 6], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0]]], 16],
+        ]
+
+for test in tests:
+    result = solution(*test[0])
+    print(test[0], result == test[1], result, test[1])