All language subtitles for 24 - Depth First Search English

In the last video you saw how I walk through how to do a breath first search in this video.

I'm going to explain how depth first search works and what depth first search is is a nother kind of

searching algorithm and it has some very different applications than breath first search and you'll

see how it works.

When I walk through the actual visualization and one other thing you may if you're familiar with the

video I did on post order binary search tree traversals.

You're going to see a few similarities between that and this.

So I'm going to start off by giving you the properties and what the properties are is you start at the

root and you follow the leftmost branch of the tree as far as possible until you either find the new

you you're looking for or you hit a leaf node.

So as you can see right here we if we start at the root and give that one we follow

the leftmost branch so we have a 1 2 3 and a 4.

So now we had our leafnode and the second property is if a leaf node is hit continue the search at the

nearest ancestor with unexplored children.

And so this is a recursive call.

And so what it will do is there are no more nodes here because four is a leaf node.

So instead we get turn around and go with the closest ancestor which is going to be right here because

this is a ancestor is a child of three.

And so this will be five.

This will be the sixth item that we visit and then we'll go up to 7 8.

And now that we're 8 Remember we have this recursive call.

So if you ever wonder where you're going to go from here remember were always going to go to the left

most note possible.

So we're going to come down here to nine ten now.

10 is a leaf node.

So we simply go to 11 and 12 and that's it.

So this is how to do depth first search as you can see it's very different than breadth first search

where as with breath first search we started at the root followed down to this level to the third level

into the fourth.

And some of the numbering differences this is the root is always one.

But in the infer breath first search this eight was actually a four because it went one two three and

then four right here.

So that's a very important thing to know depth first search has a completely different use case then

breath first.

There are both data structures or algorithms that are extremely popular for certain applications.

I personally don't I haven't really found a need to use breadth first search or depth first search in

and day to day development but that's mainly because I build out Web applications and mobile applications

and these usually aren't used for camping or more just things that you learn to learn more about computer

science and algorithm development so they're good to have a solid understanding of but they're not things

that you're going to use on a day in day out basis unless you focus in on that as a specialty so that's

depth first search.

Please let me know if you have any questions whatsoever and I'll see the next video.