day12

day12/input.txt

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+um-end
+pk-um
+FE-il
+ay-FE
+pk-start
+end-jt
+um-FE
+RO-il
+xc-ay
+il-end
+start-EZ
+pk-FE
+xc-start
+jt-FE
+EZ-um
+pk-xc
+xc-EZ
+pk-ay
+il-ay
+jt-EZ
+jt-om
+pk-EZ

day12/solution.py

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+import time
+
+def prepare_graph(input):
+    adjacencies = {}
+    lines = (l.strip() for l in input)
+    for l in lines:
+        a, b = l.split("-")
+        if a in adjacencies.keys():
+            adjacencies[a].append(b)
+        else:
+            adjacencies[a] = [b]
+        if b in adjacencies.keys():
+            adjacencies[b].append(a)
+        else:
+            adjacencies[b] = [a]
+    return adjacencies
+
+def visit(node, visited, adj, twice):
+    paths = []
+    visited.append(node)
+    if node == "end":
+        paths.append(visited)
+    else:
+        for n in adj[node]:
+            if n.islower() and n in visited:
+                if n != "start" and not twice:
+                    paths += visit(n, visited.copy(), adj, True)
+                else:
+                    continue
+            else:
+                paths += visit(n, visited.copy(), adj, twice)
+    return paths
+
+
+def part1(input):
+    adj = prepare_graph(input)
+    paths = visit("start", [], adj, True)
+    return len(paths)
+
+def part2(input):
+    adj = prepare_graph(input)
+    paths = visit("start", [], adj, False)
+    return len(paths)
+
+def main():
+    with open("day12/input.txt") as f:
+        input =  f.readlines()
+        t0 = time.perf_counter_ns()
+        print(f"solution for part 1 is: {part1(input)}")
+        t1 = time.perf_counter_ns()
+        print(f"part 1 took {t1-t0} ns")
+        print(f"solution for part 2 is: {part2(input)}")
+        t2 = time.perf_counter_ns()
+        print(f"part 2 took {t2-t1} ns")
+
+if __name__ == "__main__":
+    main()

day12/test_input.txt

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+start-A
+start-b
+A-c
+A-b
+b-d
+A-end
+b-end

day12/test_input2.txt

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+dc-end
+HN-start
+start-kj
+dc-start
+dc-HN
+LN-dc
+HN-end
+kj-sa
+kj-HN
+kj-dc

day12/test_input3.txt

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+fs-end
+he-DX
+fs-he
+start-DX
+pj-DX
+end-zg
+zg-sl
+zg-pj
+pj-he
+RW-he
+fs-DX
+pj-RW
+zg-RW
+start-pj
+he-WI
+zg-he
+pj-fs
+start-RW