mutable struct Tree

parent

left

right

function Tree(parent)

Tree(parent, nothing, nothing)

function Base.show(io::IO, tree::Tree)

tree isa Number && return print(tree)

print("[")

print(tree.left)

print(",")

print(tree.right)

print("]")

function make_tree(list, parent=nothing)

list isa Number && return list

curr = Tree(parent)

curr.left = make_tree(list[1], curr)

curr.right = make_tree(list[2], curr)

return curr

function explode(curr, left_leaf, right_leaf)

if left_leaf != nothing

left_leaf.right isa Number ? left_leaf.right += curr.left : left_leaf.left += curr.left

end

if right_leaf != nothing

right_leaf.left isa Number ? right_leaf.left += curr.right : right_leaf.right += curr.right

end

if curr.parent.left === curr

curr.parent.left = 0

else

curr.parent.right = 0

end

return true

function find_leaves(curr, depth=0)

curr isa Number && return []

mid = curr.left isa Number || curr.right isa Number ? [(depth, curr)] : []

vcat(find_leaves(curr.left, depth+1), mid, find_leaves(curr.right, depth+1))

function find_next_explode(tree)

leaves = vcat([(0, nothing)], find_leaves(tree), [(0, nothing)])

for i in eachindex(leaves)

if leaves[i][1] >= 4 && leaves[i][2].left isa Number && leaves[i][2].right isa Number

return explode(leaves[i][2], leaves[i-1][2], leaves[i+1][2])

end

end

return false

function find_next_split(tree)

found_split = false

should_split(num) = num isa Number && num > 9

function split_descend(curr)

split_up(num) = Tree(curr, num ÷ 2, num - num ÷ 2)

curr isa Number && return false

found_split && return true

should_split(curr.left) && (curr.left = split_up(curr.left)) != 1 && return found_split = true

split_descend(curr.left) && return true

should_split(curr.right) && (curr.right = split_up(curr.right)) != 1 && return found_split = true

split_descend(curr.right) && return true

return false

end

return split_descend(tree)

function reduce_tree(tree)

i = 0

while true

find_next_explode(tree) && continue

find_next_split(tree) && continue

return tree

end

function merge_trees(left_tree, right_tree)

new_root = Tree(nothing)

left_tree.parent = new_root

right_tree.parent = new_root

new_root.left = left_tree

new_root.right = right_tree

return new_root

function add_trees(tree1, tree2)

merge_trees(tree1, tree2) |> reduce_tree

function magnitude(tree)

tree isa Number && return tree

return 3magnitude(tree.left) + 2magnitude(tree.right)

function solve_part1(trees)

curr = trees[1]

for next in trees[2:end]

merged = merge_trees(curr, next)

curr = reduce_tree(merged)

end

println(magnitude(curr))

function solve_part2(trees)

best = 0

for t1 in trees, t2 in trees

if !(t1 == t2)

best = max(best, add_trees(deepcopy(t1), deepcopy(t2)) |> magnitude)

end

end

println(best)

function main()

trees = readlines() .|> Meta.parse .|> eval .|> make_tree

solve_part1(deepcopy(trees))

solve_part2(deepcopy(trees))

main()

4140

3993

[[[0,[5,8]],[[1,7],[9,6]]],[[4,[1,2]],[[1,4],2]]]

[[[5,[2,8]],4],[5,[[9,9],0]]]

[6,[[[6,2],[5,6]],[[7,6],[4,7]]]]

[[[6,[0,7]],[0,9]],[4,[9,[9,0]]]]

[[[7,[6,4]],[3,[1,3]]],[[[5,5],1],9]]

[[6,[[7,3],[3,2]]],[[[3,8],[5,7]],4]]

[[[[5,4],[7,7]],8],[[8,3],8]]

[[9,3],[[9,9],[6,[4,9]]]]

[[2,[[7,7],7]],[[5,8],[[9,3],[0,2]]]]

[[[[5,2],5],[8,[3,7]]],[[5,[7,5]],[4,4]]]

3494

4712

[[[[3,9],[0,5]],[4,6]],3]

[[[8,[3,0]],[[8,4],[9,4]]],[[[0,9],4],[[3,8],2]]]

[3,[3,[[2,8],[1,4]]]]

[8,[[3,6],[[8,9],[4,1]]]]

[[3,[[5,8],[3,3]]],[[[9,3],[6,3]],[[7,0],[8,8]]]]

[[6,[[5,8],7]],[8,[[1,6],7]]]

[[[[8,6],[9,3]],[3,[2,7]]],[[[6,7],[2,8]],[6,7]]]

[[[9,[1,6]],0],[[7,3],[2,4]]]

[[[[4,9],3],6],[[7,5],8]]

[[[[8,3],8],[2,[6,5]]],[[6,[1,9]],[0,2]]]

[[[9,9],[[9,8],1]],[[[7,4],[1,4]],[[1,1],4]]]

[[5,[[8,2],[8,6]]],[9,[7,[8,9]]]]

[[4,6],[8,[3,[1,2]]]]

[[[2,[7,9]],7],[[2,0],[9,2]]]

[[4,9],[[[3,4],[2,9]],5]]

[[[[0,0],[3,7]],[[6,1],8]],[[[4,0],4],8]]

[[4,[[8,9],[2,2]]],[[[1,8],[2,7]],[[6,8],0]]]

[[7,5],[[7,0],1]]

[[[5,[1,0]],1],[[[7,7],[2,2]],[[4,2],8]]]

[[[7,1],[7,3]],[2,0]]

[[[[6,2],3],[3,[5,2]]],[[7,2],[[9,5],[0,1]]]]

[[[[0,3],2],6],9]

[[[9,8],[[7,8],[5,9]]],[[[4,8],[0,2]],[[6,8],[2,3]]]]

[2,[[3,7],9]]

[[[9,9],1],[7,[7,[5,8]]]]

[[8,[1,1]],[8,8]]

[[[[3,3],[1,4]],[[5,3],4]],[5,2]]

[[[[0,9],1],[[3,8],8]],[9,[[8,8],[0,7]]]]

[[[9,4],1],[[9,7],[[6,1],[9,5]]]]

[[[1,[4,0]],9],[[3,7],2]]

[[[5,[0,5]],[5,[9,2]]],[[[2,2],[8,0]],[3,[7,8]]]]

[[[[8,2],3],3],[[[5,4],[0,5]],9]]

[[[3,[6,2]],0],[[[7,3],[6,3]],[[6,3],2]]]

[[6,1],[[[1,2],2],[9,4]]]

[[[1,[9,0]],[[8,2],[4,9]]],[[0,[9,6]],[[0,4],[4,0]]]]

[9,[4,[7,0]]]

[[7,2],[[9,5],8]]

[[6,[[0,6],0]],[[[2,0],[4,1]],[[9,5],4]]]

[[[6,[0,0]],5],[[[5,2],[7,3]],[[2,8],[3,2]]]]

[[[2,7],[[8,2],2]],[[5,[0,6]],[[9,8],[0,4]]]]

[[[8,9],[[4,1],2]],[[[3,4],[4,5]],[[7,4],0]]]

[[5,[2,[2,1]]],[[5,6],[[6,2],[3,0]]]]

[[8,[0,0]],[[6,1],[9,[1,3]]]]

[[[9,[5,8]],5],[[8,[6,6]],[7,5]]]

[3,2]

[[8,[[6,3],[8,4]]],[[2,7],[8,[9,5]]]]

[[[4,[9,1]],[[3,6],[8,8]]],[[[9,0],6],[[3,7],6]]]

[[9,[[4,9],6]],[[8,2],[1,3]]]

[[[2,[4,3]],[[5,6],[7,3]]],7]

[[[[0,1],7],[[9,1],9]],[[[0,1],[6,5]],1]]

[[[7,[5,3]],[[6,6],6]],[[2,7],3]]

[[1,[[5,8],[1,7]]],[[[5,0],[4,7]],[[3,3],[3,7]]]]

[[[[8,8],[2,6]],[1,2]],[[[2,6],4],[1,[1,8]]]]

[5,[[8,[8,2]],0]]

[[6,[[5,9],[8,4]]],[7,[5,9]]]

[[7,3],[[[2,5],4],[[1,1],8]]]

[[[0,1],7],[0,8]]

[[7,[6,6]],[2,9]]

[[[[1,9],1],[[4,8],5]],[[0,[8,3]],[[0,9],[1,5]]]]

[[[0,9],[[6,7],5]],[4,[[1,1],[0,6]]]]

[[[6,1],7],[[[1,4],8],[[9,0],4]]]

[5,[3,[[0,7],[4,9]]]]

[[[[6,0],[1,5]],[[1,5],1]],[[1,[7,1]],[[6,2],7]]]

[[[9,0],8],[[[4,1],[5,4]],[4,[5,1]]]]

[3,[5,9]]

[6,[6,5]]

[[1,[8,0]],[9,0]]

[[[[1,8],3],0],[7,[[0,8],6]]]

[[[[4,2],2],3],[[2,5],[[9,2],4]]]

[[1,[[1,1],[8,4]]],[[[8,1],0],[0,2]]]

[[[[0,7],[8,7]],[9,6]],0]

[[3,7],[[1,[0,9]],[1,[7,6]]]]

[[[[3,5],[4,6]],[[7,1],[8,0]]],6]

[[7,[5,[7,7]]],[4,[5,3]]]

[1,[[[0,0],[4,6]],[7,[1,9]]]]

[[[3,7],[7,[0,6]]],[7,[5,3]]]

[[[[5,3],0],2],[[[2,7],[7,9]],[[1,4],3]]]

[[[[8,3],9],[[8,3],[7,4]]],[[4,[6,0]],[7,[3,7]]]]

[[[6,[5,0]],8],[[[4,5],3],[1,[5,9]]]]

[[7,8],[[6,8],[[8,4],[3,1]]]]

[[[2,7],[6,3]],[[0,0],4]]

[[1,[[6,5],[4,8]]],[[8,[2,7]],[[7,8],[6,8]]]]

[[[2,3],[7,7]],[0,[3,3]]]

[5,[[2,8],[2,[6,9]]]]

[[[[6,3],2],[[2,8],9]],[[[5,6],[8,0]],[[9,3],[5,0]]]]

[[[[6,2],7],[6,1]],[[[5,9],4],4]]

[[[[7,2],[0,4]],[[6,7],7]],[6,[[8,5],[9,0]]]]

[[[[9,6],8],[2,[3,7]]],6]

[[0,[[1,0],4]],[5,[[7,4],[2,4]]]]

[[[[4,4],[4,7]],[[7,4],3]],5]

[[[[8,2],[0,3]],[[7,2],1]],[[7,[1,2]],6]]

[[[3,8],[3,1]],[7,7]]

[[[6,5],[[8,7],4]],3]

[[7,[2,[2,5]]],[9,1]]

[9,2]

[[4,[2,9]],[[4,[2,9]],0]]

[[[0,2],[[2,1],[9,2]]],[[6,[8,2]],[4,[3,8]]]]

[1,[[[2,2],6],[[3,5],6]]]

[[[9,[4,8]],[1,4]],[4,[1,[9,1]]]]

[[[8,0],[[8,4],3]],9]