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‫So now we're going to create the ad edge function and ad edge is going to connect to vertices, which

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‫in this case will be represented like this.

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‫And when we add that edge, we're going to be doing this.

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‫So let's put the adjacency list back like this and we'll start writing our function.

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‫We'll pass it to vertices vertex one and vertex two.

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‫So we're going to say adjacency list at Vertex one and we'll say that Vertex one is a when we do this,

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‫it returns the value in the key value pair.

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‫So it is returning this unordered set.

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‫And because we've returned an unordered set, we can now use the member functions that are associated

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‫with unordered sets and we can say dot insert vertex two, which does this, and then we can do the

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‫same thing for the other vertex pass that one vertex one which adds a to that unordered set.

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‫So we can only do this if the two vertices that were creating an edge between exist.

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‫So we'll have this if statement that makes sure that vertex one and vertex two both exist.

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‫And if they do, we'll run these two lines of code and the if statement and will return true if one

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‫or both of them do not exist.

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‫We'll skip the if statement and we'll return false.

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‫So that is all of our code for add edge.

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‫So now let's flip over to VS Code and take a look at this.

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‫So there is our add edge member function added to our graph class and I'll scroll up and in our main

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‫function we'll create our graph with this line and that will create our two vertices A and B with these

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‫two lines and with this line, we will print that out and I'll run this and you can see that our graph

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‫contains those two vertices, but we don't have an edge between them yet, so I'm going to come up here.

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‫And I'll add this line, and this adds an edge between A and B.

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‫So now I'll run this and you can see that we now have an edge between those vertices and that is our

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‫function for ADD Edge.