oopsie, forgot part 2, had to rewrite due to speed issues

python/day12/day12_1.py

@@ -48,7 +48,7 @@ class Node:
         return children
 
 
-def a_start_search(start, goal):
+def a_star_search(start, goal):
     start_node = Node(start[0], start[1])
     start_node.g = 0
     openSet = [start_node]
@@ -86,4 +86,4 @@ def not_in_set(node, openset):
     return True
 
 
-print(a_start_search(s, e))
+print(a_star_search(s, e))

python/day12/day12_2.py

@@ -0,0 +1,75 @@
+lines = open("input.txt", "r").read().splitlines()
+
+relief = []
+starting_points = []
+points = []
+s = None
+e = None
+for i, line in enumerate(lines):
+    els = []
+    for j, letter in enumerate(line):
+        if letter == "a":
+            starting_points.append((i, j))
+        if letter == "S":
+            els.append(1)
+            s = (i, j)
+            starting_points.append((i, j))
+        elif letter == "E":
+            els.append(26)
+            e = (i, j)
+        else:
+            els.append(ord(letter) - 96)
+        points.append((i, j))
+    relief.append(els)
+
+
+def neighbours(node):
+    n = []
+    if node[0] > 0 and relief[node[0]][node[1]] + 1 >= relief[node[0] - 1][node[1]]:
+        n.append((node[0] - 1, node[1]))
+    if (
+        node[0] < len(relief) - 1
+        and relief[node[0]][node[1]] + 1 >= relief[node[0] + 1][node[1]]
+    ):
+        n.append((node[0] + 1, node[1]))
+    if node[1] > 0 and relief[node[0]][node[1]] + 1 >= relief[node[0]][node[1] - 1]:
+        n.append((node[0], node[1] - 1))
+    if (
+        node[1] < len(relief[0]) - 1
+        and relief[node[0]][node[1]] + 1 >= relief[node[0]][node[1] + 1]
+    ):
+        n.append((node[0], node[1] + 1))
+    return n
+
+
+def h(node):
+    return abs(e[0] - node[0]) + abs(e[1] - node[1])
+
+
+def a_star_search(start, goal):
+    queue = [start]
+    gscore = {x: 9999999 for x in points}
+    gscore[start] = 0
+    fscore = {x: 9999999 for x in points}
+    fscore[start] = h(start)
+    while len(queue) > 0:
+        queue = sorted({x: fscore[x] for x in queue}, key=lambda x: x[1])
+        current = queue.pop(0)
+        if current[0] == goal[0] and current[1] == goal[1]:
+            return fscore[current]
+        for n in neighbours(current):
+            newg = gscore[current] + 1
+            if newg < gscore[n]:
+                gscore[n] = newg
+                fscore[n] = newg + h(n)
+                if n not in queue:
+                    queue.append(n)
+    return None
+
+
+scenic = []
+for starting_point in starting_points:
+    scene = a_star_search(starting_point, e)
+    if scene is not None:
+        scenic.append(scene)
+print(sorted(scenic)[0])