d24

1 files changed, 174 insertions, 0 deletions

diff --git a/20/py/d24.py b/20/py/d24.py
new file mode 100644
index 0000000..457f71d
--- /dev/null
+++ b/20/py/d24.py
@@ -0,0 +1,174 @@
+import aoc20
+import sys
+from collections import defaultdict
+
+
+def draw(hset, hdict):
+    sqset = set()
+    sqdict = dict()
+    min_x = min_y = -10
+    max_x = max_y =  10
+
+    for hx, hy in hset:
+        x = 2*hx + hy
+        y = hy
+        sqset.add((x, y))
+        min_x = min(min_x, x)
+        max_x = max(max_x, x)
+        min_y = min(min_y, y)
+        max_y = max(max_y, y)
+
+    for hx, hy in hdict:
+        x = 2*hx + hy
+        y = hy
+        sqdict[(x, y)] = hdict[(hx, hy)]
+        min_x = min(min_x, x)
+        max_x = max(max_x, x)
+        min_y = min(min_y, y)
+        max_y = max(max_y, y)
+
+    s = "{} {} {} {}\n".format(min_x, max_x, min_y, max_y)
+    for y in range(min_y, max_y+1):
+        for x in range(min_x, max_x+1):
+            if (x, y) in sqset:
+                s += "*"
+            else:
+                s += " "
+
+            if (x, y) in sqdict:
+                s += str(sqdict[(x, y)])
+            else:
+                s += " "
+
+            if (x, y) in sqset:
+                s += "*"
+            else:
+                s += " "
+        s += "\n"
+    return s
+
+
+def pt1(_in):
+    # two coordinates
+    # (
+    #   x: W-E
+    #   y: SW-NE
+    # )
+    tiles = set()
+
+    for line in _in:
+        x = y = 0
+        i = 0
+        while i < len(line):
+            c = line[i]
+            i += 1
+            if c in "ns":
+                c += line[i]
+                i += 1
+
+            if c == "e":
+                x += 1
+            elif c == "se":
+                x += 1
+                y -= 1
+            elif c == "sw":
+                y -= 1
+            elif c == "w":
+                x -= 1
+            elif c == "nw":
+                x -= 1
+                y += 1
+            elif c == "ne":
+                y += 1
+
+        p = (x, y)
+        if p in tiles:
+            tiles.remove(p)
+        else:
+            tiles.add(p)
+    return(len(tiles))
+
+
+def neighbours(p):
+    #         y=+1
+    #       E F
+    # x=-1 D X A x=+1
+    #       C B
+    #    y=-1
+    x, y = p
+    return [
+        (x+1, y),
+        (x+1, y-1),
+        (x-1, y),
+        (x-1, y+1),
+        (x,   y+1),
+        (x,   y-1),
+    ]
+
+
+def pt2(_in):
+    # two coordinates
+    # (
+    #   x: W-E
+    #   y: SW-NE
+    # )
+    active = set()
+
+    for line in _in:
+        x = y = 0
+        i = 0
+        while i < len(line):
+            c = line[i]
+            i += 1
+            if c in "ns":
+                c += line[i]
+                i += 1
+
+            if c == "e":
+                x += 1
+            elif c == "se":
+                x += 1
+                y -= 1
+            elif c == "sw":
+                y -= 1
+            elif c == "w":
+                x -= 1
+            elif c == "nw":
+                x -= 1
+                y += 1
+            elif c == "ne":
+                y += 1
+
+        p = (x, y)
+        if p in active:
+            active.remove(p)
+        else:
+            active.add(p)
+
+    board = defaultdict(lambda: 0)
+    for p in active:
+        for n in neighbours(p):
+            board[n] += 1
+
+    for i in range(100):
+        new_board = defaultdict(lambda: 0)
+        new_active = set()
+        for p, deg in board.items():
+            if p in active and not (deg == 0 or deg > 2):
+                new_active.add(p)
+                for n in neighbours(p):
+                    new_board[n] += 1
+            elif p not in active and deg == 2:
+                new_active.add(p)
+                for n in neighbours(p):
+                    new_board[n] += 1
+
+        board = new_board
+        active = new_active
+    return len(active)
+
+
+if __name__ == "__main__":
+    _in = aoc20.read_input(sys.argv[1:], 24)
+    print(pt1(_in))
+    print(pt2(_in))