Solved part 1 of day 15

15/input.txt

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+11,0,1,10,5,19

15/part1.py

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+
+
+
+def getStartingNumbers(filename):
+	with open(filename, "r") as f:
+		return [int(n) for n in f.read().split(",")]
+
+numbers = getStartingNumbers("input.txt")
+occurences = {n: [i] for i,n in enumerate(numbers)}
+
+while len(numbers) < 2020:
+	lastNumber = numbers[-1]
+	if len(occurences[lastNumber]) > 1:
+		number = occurences[lastNumber][-1] - occurences[lastNumber][-2]
+	else:
+		number = 0
+	occurences[number] = occurences.get(number, [])
+	occurences[number].append(len(numbers))
+	numbers.append(number)
+
+print(numbers[2019])

15/test.txt

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+3,2,1