aoc15pt1.py

class Node():
    def __init__(self, val, pos):
        self.pos = pos
        self.td = None
        self.visited = False
        self.val = val
        self.nodes = []

    def unvisited_nodes(self):
        return [n for n in self.nodes if not n.visited]

    def __repr__(self):
        return str(self.pos)


cave = []
with open('15p.txt', 'r') as f:
    for i, line in enumerate(f):
        cave.append([Node(int(spot), (i, j)) for j, spot in enumerate(line.strip())])


for i in range(len(cave)):
    for j in range(len(cave[0])):
        node = cave[i][j]
        for k in range(-1, 2):
            for l in range(-1, 2):
                pos_x = i + k
                pos_y = j + l
                if (not (k == 0 and l == 0) and
                    pos_x >= 0 and pos_y >= 0 and
                    pos_x < len(cave) and pos_y < len(cave[0]) and
                    abs(k) + abs(l) != 2):
                    node.nodes.append(cave[pos_x][pos_y])


current = cave[0][0]
current.td = 0
end_node = cave[-1][-1]

while current != end_node:
    next_node = None
    for node in current.unvisited_nodes():
        potential = current.td + node.val
        node.td = potential if node.td is None else min(node.td, potential)
        if next_node is None or next_node.td > node.td or node == end_node:
            next_node = node
    current.visited = True
    current = next_node

print(current.td)