🐶

toolkit.py

@@ -1,3 +1,6 @@
+import collections
+
+
 def render(grid, brush):
     if isinstance(brush, str):
         brush = {i: c for i, c in enumerate(brush)}
@@ -26,3 +29,11 @@ def bsearch(fn, goal, lo, hi):
     assert goal <= b, 'higher bound too low'
 
     return lo
+
+
+def read_image(text):
+    grid = collections.defaultdict(str)
+    for y, line in enumerate(text.splitlines()):
+        for x, cell in enumerate(line):
+            grid[complex(x, y)] = cell
+    return grid

y2019/p17.py

@@ -0,0 +1,45 @@
+import re
+import sys
+
+from intcode import compute, parse
+
+from toolkit import read_image
+
+
+# part1
+text = sys.stdin.read()
+snapshot = ''.join(chr(val) for val in compute(text, 0))
+grid = read_image(snapshot)
+alignment_parameters = [
+    (pos.real, pos.imag)
+    for pos, val in grid.items()
+    if {grid.get(pos + d) for d in [0, 1, -1, 1j, -1j]} == {'#'}
+]
+print(int(sum(a * b for a, b in alignment_parameters)))
+
+# find path
+pos = {v: k for k, v in grid.items()}['^']
+ori = -1j
+path = []
+while {grid[pos + ori * rot] for rot in [1, 1j, -1j]} != {'.'}:
+    if grid[pos + ori] == '#':
+        pos += ori
+        path[-1] += 1
+    else:
+        for c, rot in [('R', 1j), ('L', -1j)]:
+            if grid[pos + ori * rot] == '#':
+                ori *= rot
+                path += [c, 0]
+full_path = ','.join(str(c) for c in path) + ','
+
+# compress
+regex = r'^(.{2,21})(?:\1)*(.{2,21})(?:\1|\2)*(.{2,21})(?:\1|\2|\3)*$'
+A, B, C = [group.strip(',') for group in re.match(regex, full_path).groups()]
+MAIN = full_path.replace(A, 'A').replace(B, 'B').replace(C, 'C').strip(',')
+
+# part2
+mem = parse(text)
+mem[0] += 1
+code = ('\n'.join([MAIN, A, B, C, 'n']) + '\n').encode()
+output = ''.join(chr(val) for val in compute(mem, iter(code)))
+print(ord(output[-1]))