Added solutions for day 10

askrepps · askrepps · commit 2d29721546e1 · 2020-12-11T19:49:45.000-05:00
diff --git a/advent2020/day10.py b/advent2020/day10.py
@@ -0,0 +1,74 @@
+# MIT License
+#
+# Copyright (c) 2020 Andrew Krepps
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+
+from . import util
+
+
+def get_adapter_differences(adapters):
+    diffs = []
+    current = 0
+    for adapter in sorted(adapters):
+        diffs.append(adapter - current)
+        current = adapter
+    diffs.append(3)
+    return diffs
+
+
+def count_arrangements(adapters):
+    sorted_adapters = sorted(adapters)
+    counts = []
+    for idx, adapter in enumerate(sorted_adapters):
+        count = 0
+        # see if adapter is compatible with outlet (0 joltage)
+        if adapter <= 3:
+            count += 1
+        # count how many previous adapters are compatible and accumulate possible connection paths
+        look_back = 1
+        while idx - look_back >= 0 and (adapter - sorted_adapters[idx - look_back]) <= 3:
+            count += counts[idx - look_back]
+            look_back += 1
+        counts.append(count)
+    return counts
+
+
+def get_part1_answer(adapters):
+    diffs = get_adapter_differences(adapters)
+    num_ones = 0
+    num_threes = 0
+    for diff in diffs:
+        if diff == 1:
+            num_ones += 1
+        elif diff == 3:
+            num_threes += 1
+    return num_ones*num_threes
+
+
+def get_part2_answer(adapters):
+    return count_arrangements(adapters)[-1]
+
+
+def run():
+    with open(util.get_input_file_path("day10.txt")) as f:
+        adapters = [int(line) for line in f if len(line.strip()) > 0]
+        print(f"The answer to part 1 is {get_part1_answer(adapters)}")
+        print(f"The answer to part 2 is {get_part2_answer(adapters)}")
diff --git a/main.py b/main.py
@@ -32,6 +32,7 @@
 from advent2020 import day7
 from advent2020 import day8
 from advent2020 import day9
+from advent2020 import day10
 
 
 day_runners = [
@@ -43,7 +44,8 @@
     lambda: day6.run(),
     lambda: day7.run(),
     lambda: day8.run(),
-    lambda: day9.run()
+    lambda: day9.run(),
+    lambda: day10.run()
 ]
 
 
diff --git a/test/test_day10.py b/test/test_day10.py
@@ -0,0 +1,87 @@
+# MIT License
+#
+# Copyright (c) 2020 Andrew Krepps
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+
+import unittest
+
+from advent2020.day10 import get_part1_answer
+from advent2020.day10 import get_part2_answer
+
+
+adapter_data1 = """
+16
+10
+15
+5
+1
+11
+7
+19
+6
+12
+4
+"""
+
+adapter_data2 = """
+28
+33
+18
+42
+31
+14
+46
+20
+48
+47
+24
+23
+49
+45
+19
+38
+39
+11
+1
+32
+25
+35
+8
+17
+7
+9
+4
+2
+34
+10
+3
+"""
+
+
+class Day10Test(unittest.TestCase):
+    def test_day10(self):
+        self.run_day10_test(adapter_data1, 35, 8)
+        self.run_day10_test(adapter_data2, 220, 19208)
+
+    def run_day10_test(self, data, expected_part1, expected_part2):
+        adapters = [int(line) for line in data.split("\n") if len(line.strip()) > 0]
+        self.assertEqual(get_part1_answer(adapters), expected_part1)
+        self.assertEqual(get_part2_answer(adapters), expected_part2)
