Question

For example ,i have a tree with such structure

let tr = Node(1,[Node(2,[Leaf(5)]);Node(3,[Leaf(6);Leaf(7)]);Leaf(4)])

How can i get a leaf with minimum depth?

Answer 1

let minDepthLeaf tree = 
    let rec aux (depth: int) = function
    | Leaf(_) as l -> (l, depth)
    | Node(_, children) -> children |> List.map (aux (depth+1)) |> List.minBy snd

    aux 0 tree |> fst