Day 16 part 2

2019/day16.py

@@ -1,42 +1,55 @@
 import math
+import sys
 
 
 def main():
     with open("day16.txt", "rt") as input_file:
         inputs = [int(i) for i in input_file.read().rstrip()]
-        # inputs = [1,2,3,4,5,6,7,8]
-        # inputs = [0,3,0,3,6,7,3,2,5,7,7,2,1,2,9,4,4,0,6,3,4,9,1,5,6,5,4,7,4,6,6,4]
 
     # Part 1
     result = phaze2phaze(inputs)
     print(f"First 8 digits: {''.join(str(int(i)) for i in result[:8])}")
 
     # Part 2
-    # offset = int(''.join(str(i) for i in inputs[:7]))
-    # rev_inputs = [i for _ in range(10000) for i in reversed(inputs)]
-    # rev_offset = len(rev_inputs) - offset
+    offset = int(''.join(str(i) for i in inputs[:7]))
+    rev_inputs = [i for _ in range(10000) for i in reversed(inputs)]
+    rev_offset = len(rev_inputs) - offset
 
-    # print(f"Offset: {offset}. Reversed offset: {rev_offset}")
-    # result = phaze2phaze(rev_inputs, index_limit=rev_offset)
-    # result_slice = result[rev_offset - 8:rev_offset]
-    # assert result_slice == [8,4,4,6,2,0,2,6]
-    # print(f"8 digits at offset: {''.join(str(int(i)) for i in result_slice)}")
+    print(f"Offset: {offset}. Reversed offset: {rev_offset}")
+    result = phaze4phaze(rev_inputs, index_limit=rev_offset + 8)
+    result_slice = result[rev_offset-8:rev_offset]
+    result_slice.reverse()
+    print(f"Answer: {''.join(str(int(i)) for i in result_slice)}")
 
 def p(index, pos):
     return round(math.cos(((pos - index + 1) // index) * (math.pi / 2)))
 
-def phaze2phaze(inputs, rounds=100, index_limit=None):
+def phaze2phaze(inputs, rounds=100):
     """ https://www.youtube.com/watch?v=i0leFvyLEF8 """
     for phase_id in range(rounds):
-        phase_id += 1
+        print_phaze(phase_id + 1)
         outputs = [None] * len(inputs)
-        print(f"Phase {phase_id}... ")
-        for index in range(index_limit or len(inputs)):
+        for index in range(len(inputs)):
             out = sum(x * p(index + 1, pos + index) for pos, x in enumerate(inputs[index:]))
             outputs[index] = abs(math.fmod(out, 10))
         inputs = outputs
     return inputs
 
+def phaze4phaze(rev_inputs, index_limit):
+    for phase_id in range(100):
+        print_phaze(phase_id + 1)
+        outputs = [None] * index_limit
+        sumsum = 0
+        for index in range(index_limit):
+            sumsum += rev_inputs[index]
+            outputs[index] = abs(math.fmod(sumsum, 10))
+        rev_inputs = outputs
+    return rev_inputs
+
+def print_phaze(n):
+    print(f"{n}... ", end="")
+    sys.stdout.flush()
+
 
 if __name__ == "__main__":
     main()