day13 paper folding

Author: shuckc

2021/day13.py

@@ -0,0 +1,74 @@
+import numpy as np
+eg = """6,10
+0,14
+9,10
+0,3
+10,4
+4,11
+6,0
+6,12
+4,1
+0,13
+10,12
+3,4
+3,0
+8,4
+1,10
+2,14
+8,10
+9,0
+
+fold along y=7
+fold along x=5
+"""
+
+def parse(eg):
+	numbers,instructions = eg.split("\n\n")
+	numbers = np.fromiter(numbers.replace("\n", ",").split(","), int).reshape([-1,2])
+	#print(numbers)
+	grid = np.zeros(shape=1+np.amax(numbers, axis=0), dtype=int)
+	t = np.transpose(numbers)
+	grid[t[0],t[1]] = 1
+	instructions = [(i[11], int(i[13:])) for i in filter(None, instructions.split('\n'))]
+	# print(grid)
+	print(instructions)
+	return np.transpose(grid), instructions
+
+def fold(grid, instructions, limit=10^6):
+	#print("grid\n{}".format(grid))
+	for i,(direction,pos) in enumerate(instructions):
+		#print(i)
+		if direction == 'y':
+			top = grid[0:pos,:]
+			bot = np.flipud(grid[pos+1:,:])
+			#print("top\n{}".format(top))
+			#print("bottom\n{}".format(bot))
+			grid = top+bot
+		else:
+			left = grid[:,0:pos]
+			right = np.fliplr(grid[:,pos+1:])
+			#print("left\n{}".format(left))
+			#print("right\n{}".format(right))
+			grid = left+right
+		grid[grid>1] = 1
+		#print("combined\n{}".format(grid))
+		print("{} dots visible".format(np.sum(grid)))
+		if i>= limit:
+			break
+	return(grid)
+
+fold(*parse(eg))
+fold(*parse(open('input/day13.txt').read()), limit=1)
+
+g = fold(*parse(open('input/day13.txt').read()))
+with np.printoptions(threshold=np.inf):
+	print(g)
+
+# [[1 1 1 1 0 1 1 1 1 0 1 0 0 0 0 1 1 1 1 0 0 0 1 1 0 0 1 1 0 0 1 1 1 0 0 1 1 1 1 0]
+#  [1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 1 0 0 1 0 1 0 0 0 0]
+#  [1 1 1 0 0 1 1 1 0 0 1 0 0 0 0 1 1 1 0 0 0 0 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 1 0 0]
+#  [1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 1 1 0 1 1 1 0 0 1 0 0 0 0]
+#  [1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 1 0 0 0 0]
+#  [1 1 1 1 0 1 0 0 0 0 1 1 1 1 0 1 0 0 0 0 0 1 1 0 0 0 1 1 1 0 1 0 0 1 0 1 0 0 0 0]]
+
+# EFLFJGRF