using recursion to print out values of a BST - javascript

Question

I'm trying to understand recursion better in Javascript with this code for a BST. I can print out a BST's values with two methods using recursion, but I can't figure out how to do it all in one method.

how can I combine

BinarySearchTree.prototype.dfs = function(node) {
  if (node) {
    console.log(node.val);
    this.dfs(node.left);
    this.dfs(node.right);
  }
}

BinarySearchTree.prototype.depthFirstTraversal = function() {
  let current = this.root;
  this.dfs(current);
}

into one function? I've been trying

BinarySearchTree.prototype.sameFunction = function(node = null) {
    // if node is null use this.root
    let current = node || this.root;
 
    if (current) {
        console.log(current.val);
        this.sameFunction(current.left);
        this.sameFunction(current.right);
    }
}

http://jsfiddle.net/rj2tyd4L/

Why? Two methods are much better here than one, because there's a clear separation of concerns: the main method applies to the whole tree, the helper method - to a particular node. — georg
– georg, Commented Oct 25, 2018 at 18:16

slider · Accepted Answer · 2018-10-25 18:17:02Z

1

What about using a second argument isRoot with it's default value set to true?

BinarySearchTree.prototype.sameFunction = function(node = null, isRoot = true) {
  let current = isRoot ? this.root : node;
  if (current) {
    console.log(current.val);
    this.sameFunction(current.left, false);
    this.sameFunction(current.right, false);
  }
}

http://jsfiddle.net/fez1jtsx/

This makes tree.sameFunction() equivalent to calling tree.depthFirstTraversal()

answered Oct 25, 2018 at 18:17

slider

13.1k1 gold badge29 silver badges45 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

totalnoob Over a year ago

thanks. any idea why this doesn't work when I make it a class method? jsfiddle.net/n8ea7ou2

slider Over a year ago

@totalnoob you missed the if statement: if (current) {...}.

Collectives™ on Stack Overflow

using recursion to print out values of a BST - javascript

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related