faulty 2021 day 15

day15.py

#!/usr/bin/env python3
#
# https://adventofcode.com/2021/day/15

import sys, os,math
from collections import deque

class Maze:
    def __init__(self, lines, size=1):
        self.size = size
        self.grid = {}
        for y, line in enumerate(lines):
            self.grid.update( { (x, y): int(ch) 
                for x, ch in enumerate(line.rstrip()) } )
        self.yrange = len(lines)
        self.xrange = len(lines[0].rstrip())
        self.exit = (self.xrange-1, self.yrange-1)

    def find_all_minimums(self):
        checked = { (0,0): 0 } # trying really hard not to count origin
        to_check = { (0,1), (1,0) }
        while to_check:
            checking, to_check = to_check, set()
            for pos in checking:
                for n in self.neighbors(pos):
                    if n in checked:
                        checked[pos] = min(checked.get(pos, math.inf), self[pos] + checked[n] )
                    else:
                        to_check.add(n)
        for y in range(10):
            for x in range(10):
                print("%3d" % checked[ (x,y) ], end='')
            print()
        return checked[ self.exit ]

    def neighbors(self, pos):
        if pos[0]>0: yield (pos[0]-1, pos[1])
        if pos[1]>0: yield (pos[0], pos[1]-1)
        if pos[0]<self.exit[0]: yield (pos[0]+1, pos[1])
        if pos[1]<self.exit[1]: yield (pos[0], pos[1]+1)

    def __getitem__(self, xy):
        return self.grid[xy]

# changes for part 2
class BigMaze(Maze):
    def __init__(self, lines):
        super().__init__(lines)
        self.exit = ((self.xrange*5)-1, (self.yrange*5)-1)

    def __getitem__(self, xy):
        x, y = xy
        if x==y==0: return 0 #origin has no risk
        px, cx = divmod(x,self.xrange)
        py, cy = divmod(y,self.yrange)
        if not (px or py):
            return self.grid[xy]
        return (self.grid[(cx,cy)]-1 + px + py) % 9 + 1


if __name__ == '__main__':
    if len(sys.argv)<2:
        print("Usage",sys.argv[0],"filename")
        sys.exit(1)
    with open(sys.argv[1]) as f:
        lines = f.readlines()

    maze = Maze(lines)
    print("part1:", maze.find_all_minimums(), "  ex == 40; p1 == 685")
    maze5 = BigMaze(lines)
    print("part2:", maze5.find_all_minimums(), "  ex == 315; p2 < 3011")