Day 8

2021/day8.py

@@ -0,0 +1,52 @@
+import sys
+
+
+def main():
+    lines = [line.rstrip() for line in sys.stdin]
+    data = [tuple(map(str.split, line.split(" | "))) for line in lines]
+
+    # Part 1
+    print(sum(
+        n in (2, 4, 3, 7)  # num enabled for 1, 4, 7, 8 resp.
+        for values in map(lambda l: l[1], data)
+        for n in map(len, values)
+    ))
+
+    # Part 2
+    print(sum(map(solve, data)))
+
+
+def solve(line):
+    patterns, values = line
+    P = [None] * 10
+    P[1] = next(p for p in patterns if len(p) == 2)  # cf
+    P[4] = next(p for p in patterns if len(p) == 4)  # bcdf
+    P[7] = next(p for p in patterns if len(p) == 3)  # acf
+    P[8] = next(p for p in patterns if len(p) == 7)  # abcdefg
+    conn_a = next(c for c in P[7] if c not in P[1])
+    P[9] = next(
+        p for p in patterns
+        if len(p) == 6 and all(c in p for c in P[4] + conn_a)
+    )
+    P[3] = next(
+        p for p in patterns
+        if len(p) == 5 and all(c in p for c in P[1])
+    )
+    conn_g = next(c for c in P[9] if c not in P[4] + conn_a)
+    conn_d = next(c for c in P[3] if c not in P[7] and c != conn_g)
+    P[0] = next(p for p in patterns if len(p) == 6 and conn_d not in p)
+    remaining = [p for p in patterns if p not in P]
+    P[6] = next(p for p in remaining if len(p) == 6)
+    remaining.remove(P[6])
+    P[5] = next(p for p in remaining if all(c in P[6] for c in p))
+    remaining.remove(P[5])
+    P[2] = remaining[0]
+    mamap = {"".join(sorted(P[i])): i for i in range(10)}
+    return sum(
+        mamap["".join(sorted(value))] * (10**i)
+        for i, value in enumerate(reversed(values))
+    )
+
+
+if __name__ == "__main__":
+    main()