hello-algo/codes/swift/chapter_hashing/hash_map_chaining.swift
Yudong Jin f68bbb0d59
Update the book based on the revised second edition (#1014)
* Revised the book

* Update the book with the second revised edition

* Revise base on the manuscript of the first edition
2023-12-28 18:06:09 +08:00

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Swift
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/**
* File: hash_map_chaining.swift
* Created Time: 2023-06-28
* Author: nuomi1 (nuomi1@qq.com)
*/
import utils
/* */
class HashMapChaining {
var size: Int //
var capacity: Int //
var loadThres: Double //
var extendRatio: Int //
var buckets: [[Pair]] //
/* */
init() {
size = 0
capacity = 4
loadThres = 2.0 / 3.0
extendRatio = 2
buckets = Array(repeating: [], count: capacity)
}
/* */
func hashFunc(key: Int) -> Int {
key % capacity
}
/* */
func loadFactor() -> Double {
Double(size / capacity)
}
/* */
func get(key: Int) -> String? {
let index = hashFunc(key: key)
let bucket = buckets[index]
// key val
for pair in bucket {
if pair.key == key {
return pair.val
}
}
// key nil
return nil
}
/* */
func put(key: Int, val: String) {
//
if loadFactor() > loadThres {
extend()
}
let index = hashFunc(key: key)
let bucket = buckets[index]
// key val
for pair in bucket {
if pair.key == key {
pair.val = val
return
}
}
// key
let pair = Pair(key: key, val: val)
buckets[index].append(pair)
size += 1
}
/* */
func remove(key: Int) {
let index = hashFunc(key: key)
let bucket = buckets[index]
//
for (pairIndex, pair) in bucket.enumerated() {
if pair.key == key {
buckets[index].remove(at: pairIndex)
}
}
size -= 1
}
/* */
func extend() {
//
let bucketsTmp = buckets
//
capacity *= extendRatio
buckets = Array(repeating: [], count: capacity)
size = 0
//
for bucket in bucketsTmp {
for pair in bucket {
put(key: pair.key, val: pair.val)
}
}
}
/* */
func print() {
for bucket in buckets {
let res = bucket.map { "\($0.key) -> \($0.val)" }
Swift.print(res)
}
}
}
@main
enum _HashMapChaining {
/* Driver Code */
static func main() {
/* */
let map = HashMapChaining()
/* */
// (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()
/* */
// key value
let name = map.get(key: 13276)
print("\n输入学号 13276 ,查询到姓名 \(name!)")
/* */
// (key, value)
map.remove(key: 12836)
print("\n删除 12836 后,哈希表为\nKey -> Value")
map.print()
}
}