Day 08

day08/part2.py

@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+
+#  a
+# b c
+#  d
+# e f
+#  g
+
+# 1   c  f  2
+# 7 a c  f  3
+# 4  bcd f  4
+# 2 a cde g 5
+# 3 a cd fg 5
+# 5 ab d fg 5
+# 0 abc efg 6
+# 6 ab defg 6
+# 9 abcd fg 6
+# 8 abcdefg 7
+
+# 1 = len(2)
+# 7 = len(3)
+# 4 = len(4)
+# 8 = len(7)
+# b ==cnt(6)
+# e ==cnt(4)
+# bd==4 - 1
+# d ==bd - b
+# 3 = len(5) and len(&1)==2
+# 5 = len(5) & b
+# 2 = len(5) and !3 and !5
+# 9 = len(6) & !e
+# 0 = len(6) & !d
+# 6 = len(6) and !9 and !0
+
+# a=7-1
+# f=cnt(9)
+# c=cnt(8) and !a
+# g=cnt(7) and !d
+
+# a b c d e f g
+# 8 6 8 7 4 9 7
+from collections import defaultdict, Counter
+
+lines = (x.strip() for x in open("input.txt"))
+result = 0
+
+for line in lines:
+    input, output = tuple(map(lambda x: x.split(), line.split(' | ')))
+    numbers = {}
+
+    # length of the numbers
+    lengths = defaultdict(set)
+    for x in input:
+        lengths[len(x)].add(x)
+
+    # count the segments
+    counts = defaultdict(set)
+    for k, v in Counter(''.join(input)).items():
+        counts[v].add(k)
+
+    # easy matching
+    numbers[1] = lengths[2].pop()
+    numbers[4] = lengths[4].pop()
+    numbers[7] = lengths[3].pop()
+    numbers[8] = lengths[7].pop()
+
+    # necessary segment matching
+    b = counts[6].pop()
+    e = counts[4].pop()
+    d = set(numbers[4]).difference(set(numbers[1])).difference({b}).pop()
+
+    for len5 in lengths[5]:
+        # 3
+        if len(set(len5).intersection(set(numbers[1]))) == 2:
+            numbers[3] = len5
+        # 5
+        if b in set(len5):
+            numbers[5] = len5
+    # 2
+    numbers[2] = lengths[5].difference({numbers[3], numbers[5]}).pop()
+
+    for len6 in lengths[6]:
+        # 0
+        if d not in set(len6):
+            numbers[0] = len6
+        # 9
+        if e not in set(len6):
+            numbers[9] = len6
+    # 6
+    numbers[6] = lengths[6].difference({numbers[0], numbers[9]}).pop()
+
+    # prepare comparison
+    numbers = {''.join(sorted(v)): k for k, v in numbers.items()}
+    output = list(''.join(sorted(v)) for v in output)
+
+    # substitute
+    substitute = list(numbers[v] for v in output)
+    result += int(''.join(map(str, substitute)))
+
+print(result)