## ~telemachus/algorithms

ref: 7efe7ef5bf2ecd1d8f8111e31064af0296325e03 algorithms/binarysearchtree.go -rw-r--r-- 1.7 KiB
7efe7ef5Peter Aronoff Add Insert and Walk functions 10 months ago
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```package algorithms

type Node struct {
parent *Node
left   *Node
right  *Node
count  int
value  int
}

type Tree struct {
root *Node
size int
}

type fn func(int)

func NewBST() *Tree {
return &Tree{}
}

func (t *Tree) Size() int {
return t.size
}

func (t *Tree) Insert(v int) {
var prevNode *Node
currNode := t.root

// Walk the tree until we find a spot to insert a new node.
for currNode != nil {
prevNode = currNode
switch {
case v < currNode.value:
currNode = currNode.left
case v > currNode.value:
currNode = currNode.right
default: // Our value is already present, so we can return early.
currNode.count++
t.size++
return
}
}

// Create a new node, place it, and increase the size of the tree.
newNode := &Node{value: v, parent: prevNode}
switch {
case prevNode == nil:
t.root = newNode
case newNode.value < prevNode.value:
prevNode.left = newNode
default:
prevNode.right = newNode
}
t.size++
}

func (t *Tree) InOrderWalk(f fn) {
if t == nil {
return
}
t.root.left.inOrderWalk(f)
f(t.root.value)
t.root.right.inOrderWalk(f)

}

func (n *Node) inOrderWalk(f fn) {
if n == nil {
return
}
n.left.inOrderWalk(f)
f(n.value)
n.right.inOrderWalk(f)
}

func (t *Tree) PreOrderWalk(f fn) {
if t == nil {
return
}
f(t.root.value)
t.root.left.preOrderWalk(f)
t.root.right.preOrderWalk(f)
}

func (n *Node) preOrderWalk(f fn) {
if n == nil {
return
}
f(n.value)
n.left.preOrderWalk(f)
n.right.preOrderWalk(f)
}

func (t *Tree) PostOrderWalk(f fn) {
if t == nil {
return
}
t.root.left.postOrderWalk(f)
t.root.right.postOrderWalk(f)
f(t.root.value)
}

func (n *Node) postOrderWalk(f fn) {
if n == nil {
return
}
n.left.postOrderWalk(f)
n.right.postOrderWalk(f)
f(n.value)
}
```