I am new to elixer, I need some help to construct binary tree from list of element(given in level order). Due to immutability i’m facing difficutly to implement this. For ex: [1, 2, 3, -1, -1, -1, -1] will be represented as: 1 / \ 2 3 Here -…

Here’s an approach that uses a pair of recursive functions: defmodule TreeNode do defstruct ~w[data left right]a end defmodule TreeBuild do @nothing -1 def run([root | rest]) do [[left, right]] = subnodes(1, rest) %TreeNode{data: root, left: left, right: right} end def subnodes…

have you tried using gb_trees from erlang? gb_trees — OTP 29.0.2 (stdlib 8.0.1)

https://stackoverflow.com/questions/73528430/build-binary-tree-from-level-order-array

Hi @chandan374 can you show what you’ve tried so far?

(…) if a node has an index i , its children are found at indices 2i+1 (for the left child) and 2i+2 (for the right) (…) Source: Arrays at Binary tree | Wikipedia With above writing code is really simple: defmodule TreeNode do defstruct ~w[data left right]a end defmodule Example do def samp…

Hi @Eiji , thanks for the help. Sorry i didn’t provided complete context in question. Above approach will work only if given input is for complete tree. Please check 1st answer of: https://stackoverflow.com/questions/37941318/how-to-build-an-incomplete-binary-tree-from-array-representation ex: F…

Have implemented one basic solution. Please ingore code quality :sweat_smile:, its my 2nd day with elixir. Approach: Provided unique id to each node, created a map that will map parent_node_id => (left_child_id, right_child_id). Once map is created, Recursively calling on root_id to build the tree…

Above approach will work only if given input is for complete tree. Actually, @Eiji ’s approach will work also for incomplete trees, as long as the missing nodes are marked with -1, like in your example [5,4,8,11,-1,17,4,7,-1,-1,-1,5, -1, -1, -1, -1]: iex(5)> Example.sample([5,4,8,11,-1,17,4,7,-1,…

[image] chandan374: For the input: [5,4,8,11,-1,17,4,7,-1,-1,-1,5, -1, -1, -1, -1] Actual tree representation: The tree representation you provided is incorrect as 5 leaf should be a left child of 17 node. Therefore I think my example is working. This is how it should look: …

[image] al2o3cr: I believe the error in your diagram is the two -1s under the -1 that’s a right-child of 4. -1s on a given level shouldn’t consume any input values in the next level. Weird … it’s like save the space no matter what (here I mean confusion of people new in topic). It’s my first …

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Build binary tree from level order array

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chandan374 August 30, 2022, 3:46am 12

Thanks everyone for quick help.