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Sets are a collection we can use for quickly checking if a value exists.

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A set can never contain multiple copies of the same value.

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Maps and sets are different, but when you look behind the scenes, a set is similar to a map, except

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a set is only going to have keys and not a key pair value like a map.

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So like maps though, there are two sets.

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Rust, give us a hash set and a B tree set.

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And again, hash set and B tree set are similar.

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So I'm only going to show you how we can use a hash set.

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So let's start out.

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By adding the hash set into our scope.

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And now we can come down here.

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We can create a mutable hash set with the new keyword.

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And like a hash map, we can have link to return.

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How many values are in our hash set as well as is empty to return a boolean on if our set is empty or

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not.

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So just like a hash map, let's begin adding in some values with the insert keyword and we'll add in

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our values.

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And in this case.

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Just add in one, two, three and four.

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And for so to print this out, we can use what's known as an iterator and we'll be able to talk a little

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bit more about readers a little bit later in this course.

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But we can do for x in.

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H.S. dot hitter.

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Now we just want to print line.

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Ed and X.

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So now if we run this.

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See our iterator and I'm going to get rid of this.

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And because that will bother me.

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But we have one, two, three and four, which is what we added in.

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So.

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To remove a value like we did in a vector, we can just say, Hey, we want to remove a reference to

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the two, and then up here we'll actually cut and paste this.

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Run it again.

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And now we only have one, three and four.

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But I'm going to comment that out just to keep our values in there.

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So now I'm going to create another hash set called HS2.

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Just for hash it two and have it be new.

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And then I'm going to come down here.

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Up here.

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And.

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Let's say one, three, five, one, three.

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Five and seven.

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Then obviously we need to change these to set, too.

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So now we have another hash set.

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With the values one, three and five in it.

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So now with sets, we are actually given some new methods.

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So the the first one we're going to talk about is intersection.

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And when you check intersection within two sets, you're going to see which values are in both sets.

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So the first way we can do this is say four X in hash set.

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Intersection and then pass in a reference to the second set and now we can print line.

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And we're going to say intersection.

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X.

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And so we see we have one and three in both sets and intersection is.

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Has printed out one in three between the two sets.

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So another way that we can do this, a more shorthand way, is we can actually say let intersection.

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Equal to a reference to the first set.

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The.

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Binary bitwise and operator, so the ampersand sign and then a reference to the second set.

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So now intersection is going to contain.

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It's going to be a set that's going to contain.

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The values that are in both sets.

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So let's print that out for X, an intersection print line, and then we're going to say shorthand way.

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And now X and we expect this to still be the same results of one and three.

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Which is what we got so that this is a shorthand, way short shorthand intersection using the bitwise.

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The excuse me, the binary bitwise and person operator reader.

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Another one that we have is union and unions going to return values that are in either the first hash

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set or the second hash set?

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So I'm only going to show you the shorthand way because otherwise it's going to be the same way above.

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Instead of it being hash set, then method called intersection, our method call would be union.

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So let's do our shorthand way and say a reference to the hash set with the binary or.

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Operator and then set.

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Two.

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So now union is going to be a set that's going to contain values that are that are in either of the

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two hash sets.

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So let's print this out.

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To see to make sure that we got the correct values union.

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And then X.

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And for union in.

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There we go.

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And now if we run this, we have union.

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One, two, three, four, five and seven.

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So we can see that we didn't have duplicate values of one or three, but we have all the values occurring

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once between the two sets.

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And then lastly, we can use we can do the difference.

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So likewise difference would be called like this, but we're going to do the shorthand way and say let

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diff equals a reference to the first hash set minus.

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So the difference between the second hash set and now we can print this out.

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And see what the difference is and we'll say diff.

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An X.

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And so with the difference, we want to see what values are in the first hash set, but not the second

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hash.

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So if we run this, we see that we have two and four.

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And that would be correct because we have two, four, and then the second hash.

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Yet we do not have two and four.

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So there are more methods we can use on a set, but these are some of the main ones.

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And as you can see, we can do a lot of logic handling very quickly on sets.

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Again, these are just some of the collections we have available to us in Rust, so feel free to check

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out more collections.

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But again, later on down the road, I do plan to show how we can create some of the data structures

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available to use in rest so that we can continue to learn and become more proficient in our rest journey.