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84 lines
1.5 KiB
Crystal

require "advent"
INPUT = input(2022, 12).lines.map(&.chars)
EDGES = {} of Tuple(Int32,Int32) => Array(Tuple(Int32, Int32))
def add_at(pos, c, x, y)
return unless y >= 0 && y < INPUT.size
return unless x >= 0 && x < INPUT[0].size
o = INPUT[y][x]
o = 'a' if o == 'S'
o = 'z' if o == 'E'
return if (c.ord-o.ord) > 1
EDGES[pos] << ({x,y});
end
def add_nearby(x, y)
c = INPUT[y][x]
c = 'a' if c == 'S'
c = 'z' if c == 'E'
if !EDGES[{x,y}]?
EDGES[{x,y}] = [] of Tuple(Int32,Int32)
end
add_at({x,y}, c, x+1, y)
add_at({x,y}, c, x-1, y)
add_at({x,y}, c, x, y+1)
add_at({x,y}, c, x, y-1)
end
from = {0,0}
to = {100,100}
INPUT.each_with_index do |row, y|
row.each_with_index do |c, x|
pos = {x, y}
add_nearby(x, y)
from = pos if c == 'E'
end
end
costs = {from => 0}
mins = {} of Tuple(Int32, Int32) => Int32
visited = Set(Tuple(Int32, Int32)).new
while !costs.empty?
k, v = costs.min_by do |k,v|
v
end
if k == to
puts "Found! #{v}"
break
end
costs.delete k
mins[k] = v
visited << k
INPUT[k[1]][k[0]] = INPUT[k[1]][k[0]].upcase
puts k
EDGES[k].each do |edge|
next if visited.includes? edge
if old = costs[edge]?
costs[edge] = v+1 if old > v+1
else
costs[edge] = v+1
end
end
end
lengths = [] of Int32
puts mins
INPUT.each_with_index do |line, y|
line.each_with_index do |c, x|
next unless c == 'A'
if amin = mins[{x,y}]?
lengths << amin
end
print c
end
puts
end
puts lengths.min