RosettaCodeData/Task/Tree-traversal/Logo/tree-traversal.logo

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; nodes are [data left right], use "first" to get data
to node.left :node
if empty? butfirst :node [output []]
output first butfirst :node
end
to node.right :node
if empty? butfirst :node [output []]
if empty? butfirst butfirst :node [output []]
output first butfirst butfirst :node
end
to max :a :b
output ifelse :a > :b [:a] [:b]
end
to tree.depth :tree
if empty? :tree [output 0]
output 1 + max tree.depth node.left :tree tree.depth node.right :tree
end
to pre.order :tree :action
if empty? :tree [stop]
invoke :action first :tree
pre.order node.left :tree :action
pre.order node.right :tree :action
end
to in.order :tree :action
if empty? :tree [stop]
in.order node.left :tree :action
invoke :action first :tree
in.order node.right :tree :action
end
to post.order :tree :action
if empty? :tree [stop]
post.order node.left :tree :action
post.order node.right :tree :action
invoke :action first :tree
end
to at.depth :n :tree :action
if empty? :tree [stop]
ifelse :n = 1 [invoke :action first :tree] [
at.depth :n-1 node.left :tree :action
at.depth :n-1 node.right :tree :action
]
end
to level.order :tree :action
for [i 1 [tree.depth :tree]] [at.depth :i :tree :action]
end
make "tree [1 [2 [4 [7]]
[5]]
[3 [6 [8]
[9]]]]
pre.order :tree [(type ? "| |)] (print)
in.order :tree [(type ? "| |)] (print)
post.order :tree [(type ? "| |)] (print)
level.order :tree [(type ? "| |)] (print)