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feat: add Swift codes for hash_collision article (#569)
* feat: add Swift codes for hash_collision article * refactor: extract common Pair * Update hash_map.md --------- Co-authored-by: Yudong Jin <krahets@163.com>
This commit is contained in:
parent
69920a0599
commit
7f8b0fff54
6 changed files with 335 additions and 12 deletions
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@ -27,6 +27,8 @@ let package = Package(
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// chapter_hashing
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.executable(name: "hash_map", targets: ["hash_map"]),
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.executable(name: "array_hash_map", targets: ["array_hash_map"]),
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.executable(name: "hash_map_chaining", targets: ["hash_map_chaining"]),
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.executable(name: "hash_map_open_addressing", targets: ["hash_map_open_addressing"]),
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// chapter_tree
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.executable(name: "binary_tree", targets: ["binary_tree"]),
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.executable(name: "binary_tree_bfs", targets: ["binary_tree_bfs"]),
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@ -90,7 +92,9 @@ let package = Package(
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.executableTarget(name: "array_deque", path: "chapter_stack_and_queue", sources: ["array_deque.swift"]),
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// chapter_hashing
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.executableTarget(name: "hash_map", dependencies: ["utils"], path: "chapter_hashing", sources: ["hash_map.swift"]),
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.executableTarget(name: "array_hash_map", path: "chapter_hashing", sources: ["array_hash_map.swift"]),
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.executableTarget(name: "array_hash_map", dependencies: ["utils"], path: "chapter_hashing", sources: ["array_hash_map.swift"]),
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.executableTarget(name: "hash_map_chaining", dependencies: ["utils"], path: "chapter_hashing", sources: ["hash_map_chaining.swift"]),
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.executableTarget(name: "hash_map_open_addressing", dependencies: ["utils"], path: "chapter_hashing", sources: ["hash_map_open_addressing.swift"]),
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// chapter_tree
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.executableTarget(name: "binary_tree", dependencies: ["utils"], path: "chapter_tree", sources: ["binary_tree.swift"]),
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.executableTarget(name: "binary_tree_bfs", dependencies: ["utils"], path: "chapter_tree", sources: ["binary_tree_bfs.swift"]),
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@ -4,16 +4,7 @@
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* 键值对 */
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class Pair {
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var key: Int
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var val: String
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init(key: Int, val: String) {
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self.key = key
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self.val = val
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}
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}
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import utils
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/* 基于数组简易实现的哈希表 */
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class ArrayHashMap {
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137
codes/swift/chapter_hashing/hash_map_chaining.swift
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137
codes/swift/chapter_hashing/hash_map_chaining.swift
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@ -0,0 +1,137 @@
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/**
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* File: hash_map_chaining.swift
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* Created Time: 2023-06-28
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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import utils
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/* 链式地址哈希表 */
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class HashMapChaining {
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var size: Int // 键值对数量
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var capacity: Int // 哈希表容量
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var loadThres: Double // 触发扩容的负载因子阈值
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var extendRatio: Int // 扩容倍数
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var buckets: [[Pair]] // 桶数组
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/* 构造方法 */
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init() {
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size = 0
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capacity = 4
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loadThres = 2 / 3
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extendRatio = 2
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buckets = Array(repeating: [], count: capacity)
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}
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/* 哈希函数 */
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func hashFunc(key: Int) -> Int {
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key % capacity
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}
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/* 负载因子 */
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func loadFactor() -> Double {
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Double(size / capacity)
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}
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/* 查询操作 */
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func get(key: Int) -> String? {
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let index = hashFunc(key: key)
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let bucket = buckets[index]
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// 遍历桶,若找到 key 则返回对应 val
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for pair in bucket {
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if pair.key == key {
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return pair.val
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}
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}
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// 若未找到 key 则返回 nil
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return nil
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}
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/* 添加操作 */
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func put(key: Int, val: String) {
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// 当负载因子超过阈值时,执行扩容
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if loadFactor() > loadThres {
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extend()
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}
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let index = hashFunc(key: key)
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let bucket = buckets[index]
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// 遍历桶,若遇到指定 key ,则更新对应 val 并返回
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for pair in bucket {
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if pair.key == key {
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pair.val = val
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return
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}
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}
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// 若无该 key ,则将键值对添加至尾部
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let pair = Pair(key: key, val: val)
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buckets[index].append(pair)
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size += 1
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}
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/* 删除操作 */
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func remove(key: Int) {
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let index = hashFunc(key: key)
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let bucket = buckets[index]
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// 遍历桶,从中删除键值对
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for (pairIndex, pair) in bucket.enumerated() {
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if pair.key == key {
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buckets[index].remove(at: pairIndex)
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}
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}
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size -= 1
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}
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/* 扩容哈希表 */
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func extend() {
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// 暂存原哈希表
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let bucketsTmp = buckets
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// 初始化扩容后的新哈希表
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capacity *= extendRatio
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buckets = Array(repeating: [], count: capacity)
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size = 0
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// 将键值对从原哈希表搬运至新哈希表
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for bucket in bucketsTmp {
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for pair in bucket {
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put(key: pair.key, val: pair.val)
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}
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}
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}
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/* 打印哈希表 */
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func print() {
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for bucket in buckets {
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let res = bucket.map { "\($0.key) -> \($0.val)" }
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Swift.print(res)
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}
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}
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}
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@main
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enum _HashMapChaining {
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/* Driver Code */
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static func main() {
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/* 初始化哈希表 */
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let map = HashMapChaining()
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/* 添加操作 */
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// 在哈希表中添加键值对 (key, value)
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map.put(key: 12836, val: "小哈")
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map.put(key: 15937, val: "小啰")
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map.put(key: 16750, val: "小算")
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map.put(key: 13276, val: "小法")
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map.put(key: 10583, val: "小鸭")
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print("\n添加完成后,哈希表为\nKey -> Value")
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map.print()
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/* 查询操作 */
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// 向哈希表输入键 key ,得到值 value
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let name = map.get(key: 13276)
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print("\n输入学号 13276 ,查询到姓名 \(name!)")
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/* 删除操作 */
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// 在哈希表中删除键值对 (key, value)
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map.remove(key: 12836)
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print("\n删除 12836 后,哈希表为\nKey -> Value")
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map.print()
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}
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}
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158
codes/swift/chapter_hashing/hash_map_open_addressing.swift
Normal file
158
codes/swift/chapter_hashing/hash_map_open_addressing.swift
Normal file
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@ -0,0 +1,158 @@
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/**
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* File: hash_map_open_addressing.swift
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* Created Time: 2023-06-28
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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import utils
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/* 开放寻址哈希表 */
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class HashMapOpenAddressing {
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var size: Int // 键值对数量
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var capacity: Int // 哈希表容量
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var loadThres: Double // 触发扩容的负载因子阈值
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var extendRatio: Int // 扩容倍数
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var buckets: [Pair?] // 桶数组
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var removed: Pair // 删除标记
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/* 构造方法 */
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init() {
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size = 0
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capacity = 4
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loadThres = 2 / 3
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extendRatio = 2
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buckets = Array(repeating: nil, count: capacity)
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removed = Pair(key: -1, val: "-1")
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}
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/* 哈希函数 */
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func hashFunc(key: Int) -> Int {
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key % capacity
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}
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/* 负载因子 */
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func loadFactor() -> Double {
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Double(size / capacity)
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}
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/* 查询操作 */
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func get(key: Int) -> String? {
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let index = hashFunc(key: key)
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// 线性探测,从 index 开始向后遍历
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for i in stride(from: 0, to: capacity, by: 1) {
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// 计算桶索引,越过尾部返回头部
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let j = (index + i) % capacity
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// 若遇到空桶,说明无此 key ,则返回 nil
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if buckets[j] == nil {
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return nil
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}
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// 若遇到指定 key ,则返回对应 val
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if buckets[j]?.key == key, buckets[j] != removed {
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return buckets[j]?.val
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}
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}
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return nil
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}
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/* 添加操作 */
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func put(key: Int, val: String) {
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// 当负载因子超过阈值时,执行扩容
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if loadFactor() > loadThres {
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extend()
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}
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let index = hashFunc(key: key)
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// 线性探测,从 index 开始向后遍历
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for i in stride(from: 0, through: capacity, by: 1) {
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// 计算桶索引,越过尾部返回头部
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let j = (index + i) % capacity
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// 若遇到空桶、或带有删除标记的桶,则将键值对放入该桶
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if buckets[j] == nil || buckets[j] == removed {
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buckets[j] = Pair(key: key, val: val)
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size += 1
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return
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}
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// 若遇到指定 key ,则更新对应 val
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if buckets[j]?.key == key {
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buckets[j]?.val = val
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return
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}
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}
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}
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/* 删除操作 */
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func remove(key: Int) {
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let index = hashFunc(key: key)
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// 线性探测,从 index 开始向后遍历
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for i in stride(from: 0, to: capacity, by: 1) {
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// 计算桶索引,越过尾部返回头部
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let j = (index + i) % capacity
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// 若遇到空桶,说明无此 key ,则直接返回
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if buckets[j] == nil {
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return
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}
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// 若遇到指定 key ,则标记删除并返回
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if buckets[j]?.key == key {
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buckets[j] = removed
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size -= 1
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return
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}
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}
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}
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/* 扩容哈希表 */
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func extend() {
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// 暂存原哈希表
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let bucketsTmp = buckets
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// 初始化扩容后的新哈希表
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capacity *= extendRatio
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buckets = Array(repeating: nil, count: capacity)
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size = 0
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// 将键值对从原哈希表搬运至新哈希表
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for pair in bucketsTmp {
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if let pair, pair != removed {
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put(key: pair.key, val: pair.val)
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}
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}
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}
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/* 打印哈希表 */
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func print() {
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for pair in buckets {
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if let pair {
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Swift.print("\(pair.key) -> \(pair.val)")
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} else {
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Swift.print("null")
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}
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}
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}
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}
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@main
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enum _HashMapOpenAddressing {
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/* Driver Code */
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static func main() {
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/* 初始化哈希表 */
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let map = HashMapOpenAddressing()
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/* 添加操作 */
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// 在哈希表中添加键值对 (key, value)
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map.put(key: 12836, val: "小哈")
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map.put(key: 15937, val: "小啰")
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map.put(key: 16750, val: "小算")
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map.put(key: 13276, val: "小法")
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map.put(key: 10583, val: "小鸭")
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print("\n添加完成后,哈希表为\nKey -> Value")
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map.print()
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/* 查询操作 */
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// 向哈希表输入键 key ,得到值 value
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let name = map.get(key: 13276)
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print("\n输入学号 13276 ,查询到姓名 \(name!)")
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/* 删除操作 */
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// 在哈希表中删除键值对 (key, value)
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map.remove(key: 16750)
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print("\n删除 16750 后,哈希表为\nKey -> Value")
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map.print()
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}
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}
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20
codes/swift/utils/Pair.swift
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20
codes/swift/utils/Pair.swift
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/**
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* File: Pair.swift
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* Created Time: 2023-06-28
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* 键值对 */
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public class Pair: Equatable {
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public var key: Int
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public var val: String
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public init(key: Int, val: String) {
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self.key = key
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self.val = val
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}
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public static func == (lhs: Pair, rhs: Pair) -> Bool {
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lhs.key == rhs.key && lhs.val == rhs.val
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}
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}
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@ -515,7 +515,20 @@ index = hash(key) % capacity
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=== "Swift"
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```swift title="array_hash_map.swift"
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[class]{Pair}-[func]{}
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/* 键值对 */
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public class Pair: Equatable {
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public var key: Int
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public var val: String
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public init(key: Int, val: String) {
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self.key = key
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self.val = val
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}
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public static func == (lhs: Pair, rhs: Pair) -> Bool {
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lhs.key == rhs.key && lhs.val == rhs.val
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}
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}
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[class]{ArrayHashMap}-[func]{}
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```
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