hello-algo/codes/swift/chapter_hashing/array_hash_map.swift

/**
 * File: array_hash_map.swift
 * Created Time: 2023-01-16
 * Author: nuomi1 (nuomi1@qq.com)
 */

/* 键值对 int->String */
class Entry {
    var key: Int
    var val: String

    init(key: Int, val: String) {
        self.key = key
        self.val = val
    }
}

/* 基于数组简易实现的哈希表 */
class ArrayHashMap {
    private var buckets: [Entry?] = []

    init() {
        // 初始化数组，包含 100 个桶
        for _ in 0 ..< 100 {
            buckets.append(nil)
        }
    }

    /* 哈希函数 */
    private func hashFunc(key: Int) -> Int {
        let index = key % 100
        return index
    }

    /* 查询操作 */
    func get(key: Int) -> String? {
        let index = hashFunc(key: key)
        let pair = buckets[index]
        return pair?.val
    }

    /* 添加操作 */
    func put(key: Int, val: String) {
        let pair = Entry(key: key, val: val)
        let index = hashFunc(key: key)
        buckets[index] = pair
    }

    /* 删除操作 */
    func remove(key: Int) {
        let index = hashFunc(key: key)
        // 置为 nil ，代表删除
        buckets[index] = nil
    }

    /* 获取所有键值对 */
    func entrySet() -> [Entry] {
        var entrySet: [Entry] = []
        for pair in buckets {
            if let pair = pair {
                entrySet.append(pair)
            }
        }
        return entrySet
    }

    /* 获取所有键 */
    func keySet() -> [Int] {
        var keySet: [Int] = []
        for pair in buckets {
            if let pair = pair {
                keySet.append(pair.key)
            }
        }
        return keySet
    }

    /* 获取所有值 */
    func valueSet() -> [String] {
        var valueSet: [String] = []
        for pair in buckets {
            if let pair = pair {
                valueSet.append(pair.val)
            }
        }
        return valueSet
    }

    /* 打印哈希表 */
    func print() {
        for entry in entrySet() {
            Swift.print("\(entry.key) -> \(entry.val)")
        }
    }
}

@main
enum _ArrayHashMap {
    /* Driver Code */
    static func main() {
        /* 初始化哈希表 */
        let map = ArrayHashMap()

        /* 添加操作 */
        // 在哈希表中添加键值对 (key, value)
        map.put(key: 12836, val: "小哈")
        map.put(key: 15937, val: "小啰")
        map.put(key: 16750, val: "小算")
        map.put(key: 13276, val: "小法")
        map.put(key: 10583, val: "小鸭")
        print("\n添加完成后，哈希表为\nKey -> Value")
        map.print()

        /* 查询操作 */
        // 向哈希表输入键 key ，得到值 value
        let name = map.get(key: 15937)!
        print("\n输入学号 15937 ，查询到姓名 \(name)")

        /* 删除操作 */
        // 在哈希表中删除键值对 (key, value)
        map.remove(key: 10583)
        print("\n删除 10583 后，哈希表为\nKey -> Value")
        map.print()

        /* 遍历哈希表 */
        print("\n遍历键值对 Key->Value")
        for entry in map.entrySet() {
            print("\(entry.key) -> \(entry.val)")
        }
        print("\n单独遍历键 Key")
        for key in map.keySet() {
            print(key)
        }
        print("\n单独遍历值 Value")
        for val in map.valueSet() {
            print(val)
        }
    }
}