2023.11.02

challenges/2023/11-cosmicExpansion/main.py

@@ -16,7 +16,8 @@ def parse(instr: str) -> Universe:
     res = {}
     for y, line in enumerate(instr.splitlines()):
         for x, char in enumerate(line):
-            res[(x, y)] = char
+            if char != ".":
+                res[(x, y)] = char
     return res
 
 
@@ -26,7 +27,7 @@ def print_coord_grid(universe: Universe):
 
     for y in range(n_y):
         for x in range(n_x):
-            _debug(universe[(x, y)], end="")
+            _debug(universe.get((x, y), "."), end="")
         _debug()
 
 
@@ -38,7 +39,7 @@ def get_universe_y_size(universe: Universe):
     return max(map(lambda x: x[1], universe.keys())) + 1
 
 
-def expand_universe(universe: Universe):
+def expand_universe(universe: Universe, n: int):
     n_x = get_universe_x_size(universe)
     n_y = get_universe_y_size(universe)
 
@@ -48,7 +49,7 @@ def expand_universe(universe: Universe):
     for y in reversed(range(n_y)):
         all_are_empty = True
         for x in range(n_x):
-            if universe[(x, y)] != ".":
+            if universe.get((x, y)) is not None:
                 all_are_empty = False
                 break
 
@@ -58,7 +59,7 @@ def expand_universe(universe: Universe):
     for x in reversed(range(n_x)):
         all_are_empty = True
         for y in range(n_y):
-            if universe[(x, y)] != ".":
+            if universe.get((x, y)) is not None:
                 all_are_empty = False
                 break
 
@@ -66,86 +67,52 @@ def expand_universe(universe: Universe):
             expand_cols.append(x)
 
     for src_col_x in reversed(sorted(expand_cols)):
-        for x in reversed(range(src_col_x + 1, get_universe_x_size(universe) + 1)): # we don't want to touch the starting col but we do want to overflow by one
-            for y in range(n_y):
-                universe[(x, y)] = universe[(x - 1, y)]
-
-    n_x = get_universe_x_size(universe)
+        exp = [galaxy for galaxy in universe if galaxy[0] > src_col_x]
+        for galaxy in exp:
+            (gx, gy) = galaxy
+            v = universe[galaxy]
+            del universe[galaxy]
+            universe[(gx+n, gy)] = v
 
     for src_row_y in reversed(sorted(expand_rows)):
-        for y in reversed(range(src_row_y + 1, get_universe_y_size(universe) + 1)): # we don't want to touch the starting col but we do want to overflow by one
-            for x in range(n_x):
-                universe[(x, y)] = universe[(x, y - 1)]
+        exp = [galaxy for galaxy in universe if galaxy[1] > src_row_y]
+        for galaxy in exp:
+            (gx, gy) = galaxy
+            v = universe[galaxy]
+            del universe[galaxy]
+            universe[(gx, gy+n)] = v
 
 
-# def heuristic(a: Coordinate, b: Coordinate) -> float:
-#     (c, d) = a
-#     (e, f) = b
-#     return math.sqrt((e - c) ** 2 + (f - d) ** 2)
-
-
-# def get_shortest_path_len(universe: Universe, start: Coordinate, end: Coordinate) -> int:
-#     d = {start: 0}
-#     h = {start: 0}
-#     p = {}
-#     f = {}
-
-#     while end not in d:
-#         w = min(filter(lambda x: x[0] not in f, h.items()), key=lambda x: x[1])[0]
-#         f[w] = None
-
-#         for cardinal_dir in ((-1, 0), (1, 0), (0, -1), (0, 1)):
-#             u = apply_coord_delta(w, cardinal_dir)
-#             if u not in universe:
-#                 continue
-
-#             if u not in d or h[w] + 1 < h[u]:
-#                 d[u] = d[w] + 1
-#                 h[u] = heuristic(w, u)
-#                 p[u] = w
-
-#                 if u == end:
-#                     break
-
-#     return d[end]
-
 def get_shortest_path_len(start: Coordinate, end: Coordinate) -> int:
     (xa, ya) = start
     (xb, yb) = end
     return abs(xb - xa) + abs(yb - ya)
 
 
-def one(instr: str):
+def run(instr: str, expand_to: int) -> int:
     universe = parse(instr)
-    expand_universe(universe)
-
-    galaxies = []
-    for y in range(get_universe_y_size(universe)):
-        for x in range(get_universe_x_size(universe)):
-            if universe[(x, y)] == "#":
-                galaxies.append((x, y))
+    expand_universe(universe, expand_to - 1)
 
     galaxy_pairs = {}
-    for g in galaxies:
-        for h in galaxies:
+    for g in universe:
+        for h in universe:
             if h == g or (g, h) in galaxy_pairs or (h, g) in galaxy_pairs:
                 continue
             galaxy_pairs[(g, h)] = None
     galaxy_pairs = list(galaxy_pairs.keys())
 
     acc = 0
-    n = len(galaxy_pairs)
-    for i, (a, b) in enumerate(galaxy_pairs):
-        _debug(f"{i}/{n} - ", end="")
-        # h = heuristic(a, b)
-        sp = get_shortest_path_len(a, b)
-        _debug(h, sp)
-        acc += sp
+    for (a, b) in galaxy_pairs:
+        acc += get_shortest_path_len(a, b)
     return acc
 
 
+def one(instr: str):
+    return run(instr, 2)
+
+
 def two(instr: str):
-    return
+    return run(instr, 1_000_000)
 
 
 def _debug(*args, **kwargs):