Day 18: WIP

2019/day18.py

@@ -1,13 +1,59 @@
+import string
+
 from grid import Grid
+from vector import v2a
+
+
+EX1 = [
+    "#########",
+    "#b.A.@.a#",
+    "#########",
+]
+# reqs: 
+# a: []
+# b: [a]
+EX2 = [
+    "########################",
+    "#f.D.E.e.C.b.A.@.a.B.c.#",
+    "######################.#",
+    "#d.....................#",
+    "########################",
+]
+# reqs: 
+# a: []
+# b: [a]
+# c: [b]
+# d: [b]
+# e: [a, c]
+# f: [a, c, e, d]
+# 
+# - get a
+# - get b
+# - get c or d?
+#   - get c
+#     - get d or e?
+#   - d
 
 
 def main():
     with open("day18.txt", "rt") as input_file:
         lines = input_file.readlines()
     
-    lab = Lab(lines)
+    lab = Lab(lines=EX1)
     lab.dumb_print()
 
+    lab.find_positions()
+    pos = lab.start
+    missing_keys = list(lab.key_pos.keys())
+    obtained_keys = set("a")
+    while missing_keys:
+
+        for key, bt in lab.get_all_backtracks(pos).items():
+            steps, reqs, founds = bt
+            if len(reqs - obtained_keys) == 0:
+                print(key, "is accessible")
+        break
+
 
 class Lab(Grid):
 
@@ -15,6 +61,62 @@ class Lab(Grid):
     TILE_WALL = "#"
     TILE_START = "@"
 
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs, value_factory=lambda: " ")
+        self.start = None
+        self.key_pos = {}
+        self.door_pos = {}
+
+    def find_positions(self):
+        for x, y, v in self.values_gen():
+            if v == Lab.TILE_START:
+                self.start = (x, y)
+            if v in string.ascii_lowercase:
+                self.key_pos[v] = (x, y)
+            if v in string.ascii_uppercase:
+                self.door_pos[v] = (x, y)
+        self.setv(self.start[0], self.start[1], Lab.TILE_PATH)
+    
+    def get_all_backtracks(self, start):
+        return {
+            kname: self.backtrack(self.path(start, kpos), kpos, start)
+            for kname, kpos in self.key_pos.items()
+        }
+
+    def path(self, s, e):
+        discovered = Grid(value_factory=bool)
+        discovered.setv(s[0], s[1], True)
+        parents = {}
+        q = [s]
+        while q:
+            pos = q.pop(0)
+            if pos == e:
+                return parents
+            nears = self.near_objects(pos)
+            for near_pos, near_tile in nears.items():
+                if near_tile == Lab.TILE_WALL:
+                    continue
+                if discovered.getv(near_pos[0], near_pos[1]):
+                    continue
+                discovered.setv(near_pos[0], near_pos[1], True)
+                parents[near_pos] = pos
+                q.append(near_pos)
+        return parents
+
+    def backtrack(self, parents, pos, end):
+        count = 0
+        requirements = set()
+        keys_found = set()
+        while pos != end:
+            pos = parents[pos]
+            count += 1
+            tile = self.getv(pos[0], pos[1])
+            if tile in string.ascii_uppercase:
+                requirements.add(tile.lower())
+            elif tile in string.ascii_lowercase:
+                keys_found.add(tile)
+        return count, requirements, keys_found
+
 
 if __name__ == "__main__":
     main()

2019/grid.py

@@ -5,25 +5,30 @@ from collections import defaultdict
 
 class Grid:
 
-    def __init__(self, lines=None):
-        self.g = defaultdict(lambda: defaultdict(int))
+    def __init__(self, value_factory=int, lines=None):
+        self.g = defaultdict(lambda: defaultdict(value_factory))
         if lines:
             self.load(lines)
 
-    def load(self, lines, f=lambda v: v):
-        for y, line in enumerate(lines):
-            for x, c in enumerate(line.rstrip()):
-                self.g[y][x] = f(c)
-
     def getv(self, x, y):
         return self.g[y][x]
     
     def setv(self, x, y, value):
         self.g[y][x] = value
 
-    def near_items(self, p):
+    def load(self, lines, f=lambda v: v):
+        for y, line in enumerate(lines):
+            for x, c in enumerate(line.rstrip()):
+                self.g[y][x] = f(c)
+
+    def values_gen(self):
+        for y, row in self.g.items():
+            for x, v in row.items():
+                yield (x, y, v)
+
+    def near_objects(self, p):
         """Return a dict of neighbor positions to values (U, L, D, R)."""
-        return {pos: self.g[pos[1]][pos[0]] for pos in Grid.near(p)}
+        return {q: self.g[q[1]][q[0]] for q in Grid.near(p)}
 
     def dumb_print(self, f=lambda v: v):
         for row in self.g.values():
@@ -31,22 +36,12 @@ class Grid:
                 print(f(x), end="")
             print()
 
-    def print_near(self, p):
-        print("".join([
-            chr(self.g[p[1] - 1][p[0] - 1]),
-            chr(self.g[p[1] - 1][p[0]]),
-            chr(self.g[p[1] - 1][p[0] + 1]),
-        ]))
-        print("".join([
-            chr(self.g[p[1]    ][p[0] - 1]),
-            chr(self.g[p[1]    ][p[0]]),
-            chr(self.g[p[1]    ][p[0] + 1]),
-        ]))
-        print("".join([
-            chr(self.g[p[1] + 1][p[0] - 1]),
-            chr(self.g[p[1] + 1][p[0]]),
-            chr(self.g[p[1] + 1][p[0] + 1]),
-        ]))
+    def print_near(self, p, view_size=2):
+        for dy in range(-view_size, view_size + 1):
+            print("".join([
+                self.g[p[1] + dy][p[0] + dx]
+                for dx in range(-view_size, view_size + 1)
+            ]))
 
     @staticmethod
     def near(p):