implement binary search tree

Author: himanshub16

data-structures/binary-tree/binary-search-tree.go

@@ -0,0 +1,101 @@
+// Binary search tree
+// https://en.wikipedia.org/wiki/Binary_search_tree
+
+package binarySearchTree
+
+// package main
+
+import "fmt"
+
+type node struct {
+	val   int
+	left  *node
+	right *node
+}
+
+type tree struct {
+	root *node
+}
+
+func newNode(val int) *node {
+	return &node{val, nil, nil}
+}
+
+func inorder(n *node) {
+	if n != nil {
+		inorder(n.left)
+		fmt.Print(n.val, " ")
+		inorder(n.right)
+	}
+}
+
+func insert(root *node, val int) *node {
+	if root == nil {
+		return newNode(val)
+	}
+	if val < root.val {
+		root.left = insert(root.left, val)
+	} else {
+		root.right = insert(root.right, val)
+	}
+	return root
+}
+
+func inorderSuccessor(root *node) *node {
+	cur := root
+	for cur.left != nil {
+		cur = cur.left
+	}
+	return cur
+}
+
+func bst_delete(root *node, val int) *node {
+	if root == nil {
+		return nil
+	}
+	if val < root.val {
+		root.left = bst_delete(root.left, val)
+	} else if val > root.val {
+		root.right = bst_delete(root.right, val)
+	} else {
+		// this is the node to delete
+
+		// node with one child
+		if root.left == nil {
+			root = root.right
+		} else if root.right == nil {
+			root = root.left
+		} else {
+			// node with two children
+			d := inorderSuccessor(root)
+			root.val = d.val
+			root.right = bst_delete(root.right, d.val)
+		}
+	}
+	return root
+}
+
+/*
+func main() {
+	t := &tree{nil}
+	inorder(t.root)
+	t.root = insert(t.root, 10)
+	t.root = insert(t.root, 20)
+	t.root = insert(t.root, 15)
+	t.root = insert(t.root, 30)
+	inorder(t.root)
+	fmt.Print("\n")
+	t.root = bst_delete(t.root, 10)
+	inorder(t.root)
+	fmt.Print("\n")
+	t.root = bst_delete(t.root, 30)
+	inorder(t.root)
+	fmt.Print("\n")
+	t.root = bst_delete(t.root, 15)
+	inorder(t.root)
+	fmt.Print("\n")
+	t.root = bst_delete(t.root, 20)
+	inorder(t.root)
+	fmt.Print("\n")
+}
+*/