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‫So the binary tree we looked at in the last video was a binary tree, but it wasn't a binary search

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‫tree.

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‫In order for it to be a binary search tree, the nodes have to be laid out in a particular way.

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‫So let's take a look at that.

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‫So let's say we have one node in our tree and we're going to add another node with a binary search tree.

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‫If the number is greater, then it's going to go on the right of that node.

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‫And if it's less, then it's going to go on the left of that node.

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‫And because 76 is greater, then we're going to place it there.

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‫Now, let's take a look at another node.

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‫The 52 is greater than 47, and we're always going to start by comparing it to the node at the top.

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‫And because it's greater, then we're going to go to the right.

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‫But there's already a node there.

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‫So what we're going to do is we're going to compare that 52 to the 76 and because it's less than 76.

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‫That goes on the left of that node.

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‫So let's look at another node, a 21.

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‫We're always going to start at the top and because the spot to the left of the 47 is open.

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‫We'll place it right there.

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‫So let's just look at a few more here.

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‫We'll say 82.

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‫We'll start at the 47.

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‫It's greater than we'll go to the right.

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‫We'll compare it to the 76.

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‫It's greater than again, in this case, that spot is open.

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‫So we'll place it.

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‫18.

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‫It is less than 47.

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‫So we go to the left and we look at the 21.

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‫It's less than the 21 that spots open.

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‫So we'll place that there.

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‫And one final node, we'll start at the 47.

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‫It's less than we go left to the 21.

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‫27 is greater than the 21.

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‫So we place that on the right.

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‫So a couple of things to point out about a binary search tree.

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‫If you take any node in the binary search tree, all nodes below it to the right are going to be greater

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‫than that node.

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‫Everything on the left is going to be less than.

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‫And that is our overview.

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‫A binary search tree's.