Update day 15 solution

day-15/day-15.py

@@ -42,17 +42,8 @@ def part_2(input):
     x_size = len(input[0].strip())
     y_size = len(input)
     repeat = 5
-    nodes = {}
-    for y, line in enumerate(input):
-        for x, v in enumerate(line.strip()):
-            for i in range(repeat):
-                for j in range(repeat):
-                    xi = x + (x_size * i)
-                    yj = y + (y_size * j)
-                    vi = (int(v) + i + j)
-                    if 10 <= vi:
-                        vi -= 9
-                    nodes[(xi, yj)] = vi
+    nodes = {(x, y): int(v) for y, line in enumerate(input)
+             for x, v in enumerate(line.strip())}
     start = (0, 0)
     end = ((x_size * repeat) - 1, (y_size * repeat) - 1)
     cost = {start: 0}
@@ -74,11 +65,14 @@ def part_2(input):
             if 0 <= x < (x_size * repeat) and 0 <= y < (y_size * repeat):
                 if not (x, y) in done:
                     next.add((x, y))
-        for n in next:
-            next_cost = cur_cost + nodes[n]
-            if not n in cost or next_cost < cost[n]:
-                cost[n] = next_cost
-            queue.add(n)
+        for (x, y) in next:
+            next_cost = nodes[(x % x_size, y % y_size)] + \
+                (x // x_size) + (y // y_size)
+            if next_cost > 9:
+                next_cost -= 9
+            if not (x, y) in cost or (cur_cost + next_cost) < cost[(x, y)]:
+                cost[(x, y)] = cur_cost + next_cost
+            queue.add((x, y))
         done.add(current)
     result = cost[end]
     print("Part 2 result:", result)