Set

西瓜皮儿 2023/1/29

# 基本使用

Swift 的所有基本类型（比如 String、Int、Double 和 Bool）默认都是可哈希化的，一个set只接受一种类型

集合没有等价的简化形式。let set: Set<String>

let s = Set([1, 1, 2, 3, 2, 3, 2])
print(s); // [2, 3, 1]

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多种定义方式

var s3: Set = ["h", "a", "b", "c"];
var s2 = Set(["h", "a", "b", "c"]);
var s1: Set<String> = ["h", "a", "b", "c"];

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# count

var s = Set([1, 3])

print(s.count); // 2

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# isEmpty

var s = Set([1, 2, 3])

print(s.isEmpty); // false

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# 遍历

Set遍历是无序的

var s = Set([1, 2, 3])

for i in s {
    print(i); // 2 1 3
}

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排序遍历

var s = Set([1, 2, 3])

for i in s.sorted() {
    print(i); // 1 2 3
}

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# 增删改查

# insert

var s = Set([1, 3])

s.insert(2)
print(s); // [3, 2, 1]

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# remove

var s = Set([1, 2, 3])

print(s.remove(3)); // Optional(3)
print(s);           // [2, 1]

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# removeAll

var s = Set([1, 2, 3])

s.removeAll()
print(s);            // []

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# contains

简单包含

let s = Set([1, 2, 3])

let ans = s.contains(2)
print(ans); // true

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复杂条件

let s = Set([1, 3])

let ans = s.contains(where: {$0 % 2 == 0})
print(ans); // false

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# 交并差补（集）

# intersection

交集

var s1 = Set([1, 2, 3])
var s2 = Set([3, 4, 5])

print(s1.intersection(s2)); // [3]

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# union

并集

var s1 = Set([1, 2, 3])
var s2 = Set([3, 4, 5])

print(s1.union(s2)); // [4, 1, 5, 2, 3]

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# symmetricDifference

差集

var s1 = Set([1, 2, 3])
var s2 = Set([3, 4, 5])

print(s1.symmetricDifference(s2)); // [4, 5, 1, 2]

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# subtracting

补集

var s1 = Set([1, 2, 3])
var s2 = Set([3, 4, 5])

print(s1.subtracting(s2)); // [1, 2]
// s1 的 1，2 是 s2的补集

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# 其他判断

# 相等判断

var s1 = Set([1, 2, 3])
var s2 = Set([1, 2, 3])

print(s1 == s2); // true

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# 子集

var s1 = Set([1, 2, 3])
var s2 = Set([1, 2， 3])

// 子集判断
print(s2.isSubset(of: s1)); // true
print(s1.isSuperset(of: s2)); // true

// 子集且不相等判断
print(s2.isStrictSubset(of: s1)); // false
print(s1.isStrictSuperset(of: s2)); // false

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# 不相交判断

var s1 = Set([1, 2, 3])
var s2 = Set([4, 5])

print(s1.isDisjoint(with: s2)); // true

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# 其他操作

# randomElement

var s1 = Set([1, 2, 3])

print(s1.randomElement()); // 2

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# sorted

不改变原 Set

var s1 = Set([1, 2, 3])

print(s1.sorted(by: {$0 < $1})); // [1, 2, 3]

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Array Dictionary