added 2020/day15

Author: anight

2020/day15/run.py

@@ -0,0 +1,25 @@
+#! /usr/bin/env python3
+
+input = "20,9,11,0,1,2"
+
+spoken = list(map(int, input.split(',')))
+last = dict((n, i) for i, n in enumerate(spoken[:-1]))
+
+def play(limit):
+	while len(spoken) < limit:
+		number = spoken[-1]
+		if number in last:
+			spoken.append(len(spoken) - 1 - last[number])
+		else:
+			spoken.append(0)
+		last[number] = len(spoken) - 2
+
+# Part One
+
+play(2020)
+print(spoken[2020-1])
+
+# Part Two
+
+play(30_000_000)
+print(spoken[30_000_000-1])