Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
Binary tree, insert, exists, preorder, postorder, inorder traversal.
var insert = function(value, root) {
if (!root) {
// Create a new root.
root = { val: value };
}
else {
var current = root;
while (current) {
if (value < current.val) {
if (!current.left) {
// Insert left child.
current.left = { val: value };
break;
}
else {
current = current.left;
}
}
else if (value > current.val) {
if (!current.right) {
// Insert right child.
current.right = { val: value };
break;
}
else {
current = current.right;
}
}
else {
// This value already exists. Ignore it.
break;
}
}
}
return root;
}
var exists = function(value, root) {
var result = false;
var current = root;
while (current) {
if (value < current.val) {
current = current.left;
}
else if (value > current.val) {
current = current.right;
}
else {
result = true;
break;
}
}
return result;
}
var traversePre = function(head, callback) {
// Preorder traversal.
if (head) {
if (callback) {
callback(head.val);
}
traversePre(head.left, callback);
traversePre(head.right, callback);
}
}
var traversePost = function(head, callback) {
// Postorder traversal.
if (head) {
traversePost(head.left, callback);
traversePost(head.right, callback);
if (callback) {
callback(head.val);
}
}
}
var traverseIn = function(head, callback) {
// Inorder traversal.
if (head) {
traverseIn(head.left, callback);
if (callback) {
callback(head.val);
}
traverseIn(head.right, callback);
}
}
var traverseInIterative = function(head, callback) {
// Inorder traversal (iterative style).
var current = head;
var history = [];
// Move down to the left-most smallest value, saving all nodes on the way.
while (current) {
history.push(current);
current = current.left;
}
current = history.pop();
while (current) {
if (callback) {
callback(current.val);
}
// Move to the right, and then go down to the left-most smallest value again.
current = current.right;
while (current) {
history.push(current);
current = current.left;
}
current = history.pop();
}
}
var root = insert(10);
insert(5, root);
insert(6, root);
insert(3, root);
insert(20, root);
@CalosChen

This comment has been minimized.

Copy link

CalosChen commented Jun 27, 2017

Good, thank you. I am reading. I do not need to write it now. Aha.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.