Day 9

Author: davidaugustat

day9/day9.py

@@ -0,0 +1,54 @@
+def is_all_zeros(array):
+ return all(v == 0 for v in array)
+
+
+def find_differences(history):
+ diffs = [history]
+ while not is_all_zeros(diffs[-1]):
+ previous = diffs[-1]
+ diff = []
+ for i in range(len(previous)-1):
+ diff.append(previous[i+1] - previous[i])
+ diffs.append(diff)
+ return diffs
+
+
+def extrapolate_last(diffs):
+ extrapolated = [0]
+ for i in range(len(diffs)-2, -1, -1):
+ extrapolated.append(diffs[i][-1] + extrapolated[-1])
+ return extrapolated[-1]
+
+
+def extrapolate_first(diffs):
+ extrapolated = [0]
+ for i in range(len(diffs)-2, -1, -1):
+ extrapolated.append(diffs[i][0] - extrapolated[-1])
+ return extrapolated[-1]
+
+
+def part1(histories):
+ result = sum([extrapolate_last(find_differences(history)) for history in histories])
+ print(f"Result part 1: {result}")
+
+
+def part2(histories):
+ result = sum([extrapolate_first(find_differences(history)) for history in histories])
+ print(f"Result part 2: {result}")
+
+
+def read_data_from_file(filename):
+ histories = []
+ with open(filename) as file:
+ for line in file:
+ line_string = line.rstrip()
+ split = line_string.split()
+ histories.append([int(value) for value in split])
+ return histories
+
+
+# histories = read_data_from_file("testinput.txt")
+histories = read_data_from_file("input.txt")
+
+part1(histories)
+part2(histories)