URL

leetcode.com/problems/add-one-row-to-tree

Code

github.com/syohex/dotnet-study/blob/master/..

type Tree =
    | Leaf
    | Node of int * Tree * Tree


let addOneRow (root: Tree) (value: int) (depth: int) : Tree =
    let rec addOneRow' node d value depth =
        match node with
        | Leaf -> Leaf
        | Node (v, left, right) ->
            if d + 1 = depth then
                let newLeft = Node(value, left, Leaf)
                let newRight = Node(value, Leaf, right)
                Node(v, newLeft, newRight)
            else
                Node(v, addOneRow' left (d + 1) value depth, addOneRow' right (d + 1) value depth)

    if depth = 1 then
        Node(value, root, Leaf)
    else
        addOneRow' root 1 value depth