From a11cefa083f6b2f3033b6b45c8aaee09d9949b73 Mon Sep 17 00:00:00 2001
From: Stefan Harmuth <pennywise@drock.de>
Date: Mon, 12 Dec 2022 08:12:01 +0100
Subject: [PATCH] day12 - some slight optimizations

---
 day12.py | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/day12.py b/day12.py
index ff00d03..b086cfa 100644
--- a/day12.py
+++ b/day12.py
@@ -1,16 +1,16 @@
 from heapq import heappush, heappop
 from tools.aoc import AOCDay
-from tools.coordinate import Coordinate
+from tools.coordinate import Coordinate, DistanceAlgorithm
 from tools.grid import Grid
 from typing import Any
 
 
-def get_dijkstra_path(height_map: Grid, start: Coordinate, end: Coordinate) -> list | None:
+def get_dijkstra_path(height_map: Grid, start: Coordinate, end: Coordinate) -> int | None:
     f_costs = []
     openNodes = {}
     closedNodes = {}
 
-    openNodes[start] = (0, start.getDistanceTo(end), None)
+    openNodes[start] = (0, start.getDistanceTo(end, algorithm=DistanceAlgorithm.MANHATTAN), None)
     heappush(f_costs, (0, start))
 
     while f_costs:
@@ -28,25 +28,23 @@ def get_dijkstra_path(height_map: Grid, start: Coordinate, end: Coordinate) -> l
             if neighbour in closedNodes or height_map.get(neighbour) - 1 > height_map.get(currentCoord):
                 continue
 
-            neighbourDist = 1
-
-            targetDist = neighbour.getDistanceTo(end)
-            f_cost = targetDist + neighbourDist + currentNode[1]
+            targetDist = neighbour.getDistanceTo(end, algorithm=DistanceAlgorithm.MANHATTAN)
+            f_cost = targetDist + 1 + currentNode[1]
 
             if neighbour not in openNodes or f_cost < openNodes[neighbour][0]:
-                openNodes[neighbour] = (f_cost, currentNode[1] + neighbourDist, currentCoord)
+                openNodes[neighbour] = (f_cost, currentNode[1] + 1, currentCoord)
                 heappush(f_costs, (f_cost, neighbour))
 
     if end not in closedNodes:
         return None
     else:
+        steps = 0
         currentNode = closedNodes[end]
-        pathCoords = [end]
         while currentNode[2]:
-            pathCoords.append(currentNode[2])
+            steps += 1
             currentNode = closedNodes[currentNode[2]]
 
-        return pathCoords
+        return steps
 
 
 class Day(AOCDay):
@@ -79,7 +77,7 @@ class Day(AOCDay):
         return grid, start, end
 
     def part1(self) -> Any:
-        return len(get_dijkstra_path(*self.get_map())) - 1
+        return get_dijkstra_path(*self.get_map())
 
     def part2(self) -> Any:
         min_steps = float("inf")
@@ -87,8 +85,8 @@ class Day(AOCDay):
         for c in height_map.getActiveCells():
             if height_map.get(c) == 0:
                 steps_from_here = get_dijkstra_path(height_map, c, end)
-                if steps_from_here is not None and len(steps_from_here) < min_steps:
-                    min_steps = len(steps_from_here)
+                if steps_from_here is not None and steps_from_here + 1 < min_steps:
+                    min_steps = steps_from_here + 1
 
         return min_steps - 1