Day 16, 2017 - Parts I & II

Author: scottshepard

2017/day16.py

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+import re
+import os
+from string import ascii_lowercase
+
+class Dance:
+
+    def __init__(self, n, moves):
+        self.n = n
+        self.moves = moves
+        self.programs = list(ascii_lowercase)[:n]
+        self.end_states = []
+
+    def __str__(self):
+        return ''.join(self.programs)
+
+    def __repr__(self):
+        return str(self)
+
+    def solve_n_times(self, n):
+        for i in range(n):
+            if str(self) in self.end_states:
+                return self.end_states[n % len(self.end_states)]
+            else:
+                self.solve()
+        return str(self)
+
+    def solve(self):
+        self.end_states.append(str(self))
+        for m in self.moves:
+            self.parse_move(m)
+        return str(self)
+
+    def parse_move(self, move):
+        inst = move[0]
+        if inst == 's':
+            return self.spin(int(move[1:]))
+        if inst == 'x':
+            ab = re.findall('[0-9]+', move[1:])
+            return self.exchange(int(ab[0]), int(ab[1]))
+        if inst == 'p':
+            ab = re.findall('[a-z]+', move[1:])
+            return self.partner(ab[0], ab[1])
+
+    def spin(self, X):
+        progs = self.programs
+        self.programs = progs[len(progs)-X:] + progs[:len(progs)-X]
+        return str(self)
+
+    def exchange(self, A, B):
+        p1 = self.programs[A]
+        p2 = self.programs[B]
+        self.programs[A] = p2
+        self.programs[B] = p1
+        return str(self)
+
+    def partner(self, A, B):
+        a_i = self.programs.index(A)
+        b_i = self.programs.index(B)
+        self.programs[a_i] = B
+        self.programs[b_i] = A
+        return str(self)
+
+if __name__ == '__main__':
+    rel_path = os.path.dirname(os.path.abspath(__file__))
+    file_path = os.path.join(rel_path, "inputs/day16_test.txt")
+    test_moves = open(file_path).read().split(',')
+    d1 = Dance(5, test_moves)
+    print(d1.solve())
+
+    rel_path = os.path.dirname(os.path.abspath(__file__))
+    file_path = os.path.join(rel_path, "inputs/day16.txt")
+    moves = open(file_path).read().split(',')
+    d2 = Dance(16, moves)
+    print(d2.solve())
+    print(d2.solve_n_times(1000000000))

2017/inputs/day16.txt

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+s1,x3/4,pe/b