Add part 2 outline

mjalkio · Dec 28, 2023 · 2fae39e · 2fae39e
1 parent 431aa8b
commit 2fae39e
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Showing 2 changed files with 10 additions and 3 deletions.
diff --git a/year_2023/day09/mirage_maintenance.py b/year_2023/day09/mirage_maintenance.py
@@ -1,7 +1,7 @@
 from util import read_puzzle_input
 
 
-def sum_extrapolated_values(puzzle_input):
+def sum_extrapolated_values(puzzle_input, backwards=False):
     histories = puzzle_input.split("\n")
     extrapolated_sum = 0
     for hist in histories:
@@ -15,7 +15,7 @@ def sum_extrapolated_values(puzzle_input):
         sequences[-1].append(0)
         for i in reversed(range(len(sequences) - 1)):
             sequences[i].append(sequences[i][-1] + sequences[i + 1][-1])
-        
+
         extrapolated_sum += sequences[0][-1]
     return extrapolated_sum
 
@@ -24,4 +24,4 @@ def sum_extrapolated_values(puzzle_input):
     puzzle_input = read_puzzle_input()
 
     print(f"Part 1: {sum_extrapolated_values(puzzle_input)}")
-    print(f"Part 2: {sum_extrapolated_values(puzzle_input)}")
+    print(f"Part 2: {sum_extrapolated_values(puzzle_input, backwards=True)}")
diff --git a/year_2023/day09/test_mirage_maintenance.py b/year_2023/day09/test_mirage_maintenance.py
@@ -6,3 +6,10 @@
 
 def test_sum_extrapolated_values():
     assert sum_extrapolated_values(read_puzzle_input("test_input.txt")) == 114
+
+
+def test_sum_extrapolated_values_backwards():
+    assert (
+        sum_extrapolated_values(read_puzzle_input("test_input.txt"), backwards=True)
+        == 2
+    )