Add 2018 day 2 part 2 solution

1 files changed, 26 insertions, 0 deletions

diff --git a/2018/02/puzzle-2.py b/2018/02/puzzle-2.py
new file mode 100755
index 0000000..37ce920
--- /dev/null
+++ b/2018/02/puzzle-2.py
@@ -0,0 +1,26 @@
+#!/usr/bin/python3
+
+import itertools
+
+
+def main() -> None:
+    with open('input', 'r') as f:
+        xs = f.readlines()
+    print(next(
+        x for x in
+        itertools.starmap(common, itertools.combinations(xs, 2))
+        if x is not None
+    ), end='')
+
+
+def common(x: str, y: str) -> str | None:
+    it = (i for i, (a, b) in enumerate(zip(x, y)) if a != b)
+    i = next(it)
+    try:
+        next(it)
+    except StopIteration:
+        return x[:i] + x[i+1:]
+
+
+if __name__ == '__main__':
+    main()