Solution to problem 8 in Python

src/Year_2019/P8.py

@@ -62,5 +62,78 @@ def part_1() -> None:
             print(f"The result is {layer[1] * layer[2]}")
 
 
+# --- Part Two ---
+
+# Now you're ready to decode the image. The image is rendered by stacking the
+# layers and aligning the pixels with the same positions in each layer. The
+# digits indicate the color of the corresponding pixel: 0 is black, 1 is white,
+# and 2 is transparent.
+
+# The layers are rendered with the first layer in front and the last layer in
+# back. So, if a given position has a transparent pixel in the first and second
+# layers, a black pixel in the third layer, and a white pixel in the fourth
+# layer, the final image would have a black pixel at that position.
+
+# For example, given an image 2 pixels wide and 2 pixels tall, the image data
+# 0222112222120000 corresponds to the following image layers:
+
+# Layer 1: 02
+#          22
+
+# Layer 2: 11
+#          22
+
+# Layer 3: 22
+#          12
+
+# Layer 4: 00
+#          00
+
+# Then, the full image can be found by determining the top visible pixel in
+# each position:
+
+#     The top-left pixel is black because the top layer is 0.
+#     The top-right pixel is white because the top layer is 2 (transparent),
+# but the second layer is 1.
+#     The bottom-left pixel is white because the top two layers are 2, but the
+# third layer is 1.
+#     The bottom-right pixel is black because the only visible pixel in that
+# position is 0 (from layer 4).
+
+# So, the final image looks like this:
+
+# 01
+# 10
+
+# What message is produced after decoding your image?
+
+
+def part_2() -> None:
+    picture_size = 25 * 6
+    layers = []
+    for i in range(0, len(digits), picture_size):
+        layer = digits[i : i + picture_size]
+        layers.append(layer)
+
+    full_image = []
+    for pixel in range(picture_size):
+        for layer in layers:
+            if layer[pixel] == 2:
+                continue
+            full_image.append(layer[pixel])
+            break
+
+    for idx, pixel in enumerate(full_image):
+        if pixel == 0:
+            print(" ", end="")
+        elif pixel == 1:
+            print("X", end="")
+        elif pixel == 2:
+            print("o", end="")
+        if (idx + 1) % 25 == 0:
+            print()
+
+
 if __name__ == "__main__":
     part_1()
+    part_2()