increase speed by using a cache for positions

2020/11/code.py

@@ -7,50 +7,54 @@ def readFile() -> list:
     with open(f"{__file__.rstrip('code.py')}input.txt", "r") as f:
         return [list(line.strip()) for line in f.readlines()]
 
-def get_positions(seats: list, x: int, y: int, rx: range, ry: range, adjacent: bool) -> list:
+def get_positions(seats: list, cache: dict, x: int, y: int):
-    if adjacent: # check only adjacent tiles
+    idx = (x, y)
-        positions = [(x+i, y+j) for i in range(-1,2) for j in range(-1,2) if (i,j) != (0,0)]
+    cache[idx] = {"adjacent": [], "next_seat": []}
 
-    else: # check first seat available in direction
+    for dx in range(-1, 2):
-        positions = []
+        for dy in range(-1, 2):
-        for dx in range(-1,2):
+            if dx == 0 and dy == 0:
-            for dy in range(-1,2):
+                continue
-                if dx == 0 and dy == 0:
+            # adjacent tiles
-                    continue
+            cache[idx]["adjacent"].append((x + dx, y + dy))
-                i, j = x, y
-                while i + dx in rx and j + dy in ry:
-                    i += dx
-                    j += dy
-                    if seats[i][j] in ("L", "#"):
-                        positions.append((i, j))
-                        break
 
-    return positions
+            # next available seat
+            i, j = x, y
+            while i + dx in cache["rx"] and j + dy in cache["ry"]:
+                i += dx
+                j += dy
+                if seats[i][j] in ("L", "#"):
+                    cache[idx]["next_seat"].append((i, j))
+                    break
 
-def count(seats: list, x: int, y: int, seat: str, adjacent: bool) -> int:
+def count(seats: list, cache: dict, x: int, y: int, seat: str, selection: str) -> int:
-    rx, ry =  range(len(seats)), range(len(seats[0]))
+    return sum(1 for pos in cache[(x, y)][selection] if pos[0] in cache["rx"] and \
-    positions = get_positions(seats, x, y, rx, ry, adjacent)
+        pos[1] in cache["ry"] and seats[pos[0]][pos[1]] == seat)
-    return sum(1 for pos in positions if pos[0] in rx and pos[1] in ry and \
-        seats[pos[0]][pos[1]] == seat)
 
-def iterate(seats: list, adjacent: bool = True) -> list:
+def create_cache(seats: list) -> dict:
-    size_outer = len(seats)
+    cache = {"rx": range(len(seats)), "ry": range(len(seats[0]))}
-    size_inner = len(seats[0])
+    for x in cache["rx"]:
+        for y in cache["ry"]:
+            get_positions(seats, cache, x, y)
+    return cache
+
+def iterate(seats: list, cache: dict, adjacent: bool = True) -> list:
+    selection = "adjacent" if adjacent else "next_seat"
+    tolerance = 4 if adjacent else 5
     while True:
         tmp = [s[:] for s in seats]
 
-        for x in range(size_outer):
+        for x in cache["rx"]:
-            for y in range(size_inner):
+            for y in cache["ry"]:
                 if seats[x][y] == ".":
                     continue
 
                 elif seats[x][y] == "L":
-                    if count(seats, x, y, "#", adjacent) == 0:
+                    if count(seats, cache, x, y, "#", selection) == 0:
                         tmp[x][y] = "#"
 
                 else: # seats[x][y] == "#":
-                    tolerance = 4 if adjacent else 5
+                    if count(seats, cache, x, y, "#", selection) >= tolerance:
-                    if count(seats, x, y, "#", adjacent) >= tolerance:
                         tmp[x][y] = "L"
 
         if seats == tmp:
@@ -58,15 +62,16 @@ def iterate(seats: list, adjacent: bool = True) -> list:
         else:
             seats = tmp
 
-def part1(input: list) -> int:
+def part1(input: list, cache) -> int:
-    seats = iterate(input)
+    seats = iterate(input, cache)
     return sum([row.count("#") for row in seats])
 
-def part2(input: list) -> int:
+def part2(input: list, cache) -> int:
-    seats = iterate(input, adjacent=False)
+    seats = iterate(input, cache, adjacent=False)
     return sum([row.count("#") for row in seats])
 
 if __name__ == "__main__":
     input = readFile()
-    print(f"Part 1: {part1(input)}")
+    cache = create_cache(input)
-    print(f"Part 2: {part2(input)}")
+    print(f"Part 1: {part1(input, cache)}")
+    print(f"Part 2: {part2(input, cache)}")

2020/11/test_code.py

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: MIT
 # Copyright (c) 2020 Akumatic
 
-from code import part1, part2, iterate
+from code import part1, part2, iterate, create_cache
 
 def test():
     input = [['L', '.', 'L', 'L', '.', 'L', 'L', '.', 'L', 'L'],
@@ -14,7 +14,8 @@ def test():
         ['L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L'],
         ['L', '.', 'L', 'L', 'L', 'L', 'L', 'L', '.', 'L'],
         ['L', '.', 'L', 'L', 'L', 'L', 'L', '.', 'L', 'L']]
-    assert iterate(input) == [
+    cache = create_cache(input)
+    assert iterate(input, cache) == [
         ['#', '.', '#', 'L', '.', 'L', '#', '.', '#', '#'],
         ['#', 'L', 'L', 'L', '#', 'L', 'L', '.', 'L', '#'],
         ['L', '.', '#', '.', 'L', '.', '.', '#', '.', '.'],
@@ -25,7 +26,7 @@ def test():
         ['#', 'L', '#', 'L', '#', '#', 'L', '#', 'L', '#'],
         ['#', '.', 'L', 'L', 'L', 'L', 'L', 'L', '.', 'L'],
         ['#', '.', '#', 'L', '#', 'L', '#', '.', '#', '#']]
-    assert iterate(input, adjacent=False) == [
+    assert iterate(input, cache, adjacent=False) == [
         ['#', '.', 'L', '#', '.', 'L', '#', '.', 'L', '#'],
         ['#', 'L', 'L', 'L', 'L', 'L', 'L', '.', 'L', 'L'],
         ['L', '.', 'L', '.', 'L', '.', '.', '#', '.', '.'],
@@ -36,8 +37,8 @@ def test():
         ['L', 'L', 'L', '#', '#', '#', 'L', 'L', 'L', '#'],
         ['#', '.', 'L', 'L', 'L', 'L', 'L', '#', '.', 'L'],
         ['#', '.', 'L', '#', 'L', 'L', '#', '.', 'L', '#']]
-    assert part1(input) == 37
+    assert part1(input, cache) == 37
-    assert part2(input) == 26
+    assert part2(input, cache) == 26
     print("Passed tests for", input)
 
 if __name__ == "__main__":