Solution to problem 6 in Python

src/Year_2015/P6.py

@@ -90,5 +90,73 @@ def part_1():
     print(f"There are {lit} ligths lit")
 
 
+# --- Part Two ---
+
+# You just finish implementing your winning light pattern when you realize you
+# mistranslated Santa's message from Ancient Nordic Elvish.
+
+# The light grid you bought actually has individual brightness controls; each
+# light can have a brightness of zero or more. The lights all start at zero.
+
+# The phrase turn on actually means that you should increase the brightness of
+# those lights by 1.
+
+# The phrase turn off actually means that you should decrease the brightness of
+# those lights by 1, to a minimum of zero.
+
+# The phrase toggle actually means that you should increase the brightness of
+# those lights by 2.
+
+# What is the total brightness of all lights combined after following Santa's
+# instructions?
+
+# For example:
+
+#     turn on 0,0 through 0,0 would increase the total brightness by 1.
+#     toggle 0,0 through 999,999 would increase the total brightness by
+# 2000000.
+
+
+def apply_action_(
+    action: str,
+    coords: list[int],
+    grid: dict[tuple[int, int], int],
+) -> dict[tuple[int, int], int]:
+    if action == "off":
+        for x in range(coords[0], coords[2] + 1):
+            for y in range(coords[1], coords[3] + 1):
+                if grid[x, y] != 0:
+                    grid[x, y] -= 1
+                else:
+                    grid[x, y] = 0
+        return grid
+    elif action == "on":
+        for x in range(coords[0], coords[2] + 1):
+            for y in range(coords[1], coords[3] + 1):
+                grid[x, y] += 1
+        return grid
+    elif action == "toggle":
+        for x in range(coords[0], coords[2] + 1):
+            for y in range(coords[1], coords[3] + 1):
+                grid[x, y] += 2
+        return grid
+
+
+def part_2():
+    # Initially, all lights are off("0")
+    grid = defaultdict(int)
+    for x in range(1000):
+        for y in range(1000):
+            grid[x, y] = 0
+
+    for instruction in instructions:
+        action, *coords = get_coordinates(instruction)
+        grid = apply_action_(action, coords, grid)
+
+    brightness = sum(value for value in grid.values())
+    print(f"The total brightness is {brightness}")
+
+
 if __name__ == "__main__":
     part_1()
+    part_2()