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使用 Set 存储唯一项

跟踪成员关系并避免重复

使用 Set 存储唯一项 是 CoddyKit 上的免费 Mojo Academy 课时。这是第 3 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Mojo Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Mojo Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Track Uniqueness

When you only care whether something is present, not how many times, use a Set. It holds each item once. ✨

One Element Type

A Set takes a single element type in brackets, like Set[Int]. Every member shares that type.

var ids = Set[Int]()

Add a Member

Insert a value with add. Adding something already present simply does nothing, keeping items unique.

ids.add(7)
ids.add(7)

Duplicates Collapse

Because membership is unique, adding 7 twice leaves just one 7. A set dedupes for you automatically.

Check Membership Fast

Test presence with the in operator. This is a set core strength: answering belongs-or-not very quickly.

if 7 in ids:
    print("present")

Count the Members

Use len to see how many unique items a set holds. Duplicates never inflate this count.

var size = len(ids)

Remove a Member

Take an item out with remove. After removal the set no longer reports that value as present.

ids.remove(7)

Iterate the Set

You can loop a set to visit each member, but the order is not guaranteed. Sets care about membership, not sequence.

for x in ids:
    print(x)

Union of Two Sets

Combine sets with union to get every item from both, still with no duplicates.

var both = a.union(b)

Intersection of Two Sets

Find shared items with intersection. It keeps only the values present in both sets.

var common = a.intersection(b)

When a Set Shines

Reach for a set to remove duplicates or test membership repeatedly. It beats scanning a list every time.

Quick Check

You add the value 7 to an empty Set, then add 7 again. What is len of the set?

Recap

A Set stores unique items for fast membership tests. Use add and remove, in to check, and union or intersection to combine. 🎯

常见问题解答

「使用 Set 存储唯一项」课时是免费的吗？

是的 — 「使用 Set 存储唯一项」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Mojo Academy 课程的其余内容，请升级到 CoddyKit PRO。 Mojo Academy 课程共包含 4 节课。

「使用 Set 存储唯一项」这节课中我会学到什么？

跟踪成员关系并避免重复你通过在浏览器中直接运行的动手代码来练习 Mojo Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Mojo Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Mojo Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 3 节课，共 4 节。

「使用 Set 存储唯一项」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Mojo Academy 课中编写并运行代码吗？

能。每节 Mojo Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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