1 files changed, 50 insertions, 0 deletions
diff --git a/day13.py b/day13.py
new file mode 100644
index 0000000..a1f4058
--- /dev/null
+++ b/day13.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+
+import numpy as np
+import re
+
+split_pattern = re.compile('(x|y)=([\d]*)')
+xMax = yMax = 0
+with open('day13.txt') as data:
+    coords = []
+    for line in data:
+        if line == '\n':
+            break
+        else:
+            x, y = map(int, line.strip().split(','))
+            xMax = max(xMax, x)
+            yMax = max(yMax, y)
+            coords += [(x, y)]
+    splits = []
+    for line in data:
+        splits += [split_pattern.search(line.strip()).group(1, 2)]
+
+thermal = np.zeros((xMax+1, yMax+1)).astype(bool)
+for x, y in coords:
+    thermal[x, y] = True
+
+# part 1
+def fold_map(split):
+    # folds always fold the map in half
+    axis, val = split[0], int(split[1])
+    if axis == 'x':
+        folded = np.flip(thermal[val+1:], 0)
+        length = folded.shape[0]
+        thermal[val-length:val] = thermal[val-length:val] | folded
+        return thermal[:val]
+    else:
+        folded = np.flip(thermal[:, val+1:], 1)
+        length = folded.shape[1]
+        thermal[:, val-length:val] = thermal[:, val-length:val] | folded
+        return thermal[:, :val]
+# part 1
+print(np.count_nonzero(fold_map(splits[0])))
+
+# part 2
+for split in splits:
+    thermal = fold_map(split)
+thermal_str = thermal.astype(str)
+thermal_str[thermal] = "*"
+thermal_str[~thermal] = " "
+for line in thermal_str.T:
+    print("".join(line))