day 25

misc/advent/2017/25/a.py

@@ -0,0 +1,23 @@
+from collections import defaultdict
+
+
+def go(inp, iters):
+    machine = {}
+    for line in inp:
+        state, val, towrite, move, newstate = line.strip().split()
+        machine[(state, int(val))] = (int(towrite), move, newstate)
+
+    tape = defaultdict(int)
+    ptr = 0
+    state = "A"
+    for _ in range(iters):
+        towrite, move, state = machine[(state, tape[ptr])]
+        tape[ptr] = towrite
+        ptr = ptr + 1 if move == "R" else ptr - 1
+
+    print(sum(tape.values()), state, ptr)
+
+
+if __name__ == "__main__":
+    # go(open("sample.tt"), 6)
+    go(open("input2.txt"), 12134527)

misc/advent/2017/25/input.txt

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+
+Begin in state A.
+Perform a diagnostic checksum after 12134527 steps.
+
+In state A:
+  If the current value is 0:
+    - Write the value 1.
+    - Move one slot to the right.
+    - Continue with state B.
+  If the current value is 1:
+    - Write the value 0.
+    - Move one slot to the left.
+    - Continue with state C.
+
+In state B:
+  If the current value is 0:
+    - Write the value 1.
+    - Move one slot to the left.
+    - Continue with state A.
+  If the current value is 1:
+    - Write the value 1.
+    - Move one slot to the right.
+    - Continue with state C.
+
+In state C:
+  If the current value is 0:
+    - Write the value 1.
+    - Move one slot to the right.
+    - Continue with state A.
+  If the current value is 1:
+    - Write the value 0.
+    - Move one slot to the left.
+    - Continue with state D.
+
+In state D:
+  If the current value is 0:
+    - Write the value 1.
+    - Move one slot to the left.
+    - Continue with state E.
+  If the current value is 1:
+    - Write the value 1.
+    - Move one slot to the left.
+    - Continue with state C.
+
+In state E:
+  If the current value is 0:
+    - Write the value 1.
+    - Move one slot to the right.
+    - Continue with state F.
+  If the current value is 1:
+    - Write the value 1.
+    - Move one slot to the right.
+    - Continue with state A.
+
+In state F:
+  If the current value is 0:
+    - Write the value 1.
+    - Move one slot to the right.
+    - Continue with state A.
+  If the current value is 1:
+    - Write the value 1.
+    - Move one slot to the right.
+    - Continue with state E.

misc/advent/2017/25/input2.txt

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+A 0 1 R B
+A 1 0 L C
+B 0 1 L A
+B 1 1 R C
+C 0 1 R A
+C 1 0 L D
+D 0 1 L E
+D 1 1 L C
+E 0 1 R F
+E 1 1 R A
+F 0 1 R A
+F 1 1 R E

misc/advent/2017/25/sample.tt

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+A 0 1 R B
+A 1 0 L B
+B 0 1 L A
+B 1 1 R A