diff --git a/20/20.py b/20/20.py
new file mode 100644
index 0000000..3b575d7
--- /dev/null
+++ b/20/20.py
@@ -0,0 +1,51 @@
+import numpy as np
+
+
+def readInput(fileName) -> tuple[np.ndarray, np.ndarray]:
+	with open(fileName) as file:
+		allLines = file.read().splitlines()
+	algorithm = np.fromstring(allLines[0].replace(".", "0 ").replace("#", "1 "), int, sep=" ")
+	image = np.array([list(line.replace(".", "0").replace("#", "1")) for line in allLines[2:]], dtype=int)
+	return algorithm, image
+
+
+def apply(algorithm: np.ndarray, image: np.ndarray, fillValue: int) -> tuple[np.ndarray, int]:
+	# we need to add two more elements on every side
+	toReadFrom = np.pad(image, 2, constant_values=fillValue)
+
+	# stride must contain 3x3 array of neighbour elements for each non-border element in toReadFrom (2D x 2D)
+	strideSize = toReadFrom.shape[0] - 2
+	strideShape = strideSize, strideSize, 3, 3
+	stride = np.lib.stride_tricks.as_strided(toReadFrom, strideShape, 2 * toReadFrom.strides)
+
+	# flatten 3x3 values
+	stride = np.reshape(stride, (strideSize, strideSize, 9))
+
+	# convert right 8 bits into decimal with np.packbits (only supports np.uint8), add 256 or 0
+	codes = stride[:, :, 0] * 256 + np.packbits(stride[:, :, 1:]).reshape(strideSize, strideSize)
+
+	newImage = algorithm[codes]
+
+	# if fillValue is 0, take the first, if 1, take the last
+	newFillValue = algorithm[fillValue * 511]
+
+	return newImage, newFillValue
+
+
+def solve():
+	algorithm, startImage = readInput("input")
+
+	# Task 1
+	nextImage, newFillValue = apply(algorithm, startImage, 0)
+	finalImage, _ = apply(algorithm, nextImage, newFillValue)
+	print(np.count_nonzero(finalImage))
+
+	# Task 2
+	image = startImage
+	fillValue = 0
+	for _ in range(50):
+		image, fillValue = apply(algorithm, image, fillValue)
+	print(np.count_nonzero(image))
+
+
+solve()
diff --git a/20/input b/20/input
new file mode 100644
index 0000000..574baec
--- /dev/null
+++ b/20/input
@@ -0,0 +1,102 @@
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diff --git a/20/testInput b/20/testInput
new file mode 100644
index 0000000..8fa4bd4
--- /dev/null
+++ b/20/testInput
@@ -0,0 +1,7 @@
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