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refactor: update the hash_map_open_addressing rust codes to synchronize with java (#787)
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易春风
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@ -4,13 +4,12 @@
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* Author: xBLACICEx (xBLACKICEx@outlook.com)
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*/
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#[derive(Debug, Clone)]
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/* 键值对 */
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#[derive(Debug, Clone, PartialEq)]
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pub struct Pair {
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pub key: i32,
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pub val: String,
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}
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/* 基于数组简易实现的哈希表 */
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pub struct ArrayHashMap {
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buckets: Vec<Option<Pair>>
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@ -1,24 +1,23 @@
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/*
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* File: hash_map_open_addressing.rs
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* Created Time: 2023-07-16
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* Author: WSL0809 (wslzzy@outlook.com)
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* Author: WSL0809 (wslzzy@outlook.com), night-cruise (2586447362@qq.com)
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*/
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#![allow(non_snake_case)]
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#![allow(unused)]
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#[derive(Clone, PartialEq)]
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/* 键值对 */
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struct Pair {
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key: i32,
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val: String,
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}
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mod array_hash_map;
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use array_hash_map::Pair;
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/* 开放寻址哈希表 */
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struct HashMapOpenAddressing {
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size: usize,
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capacity: usize,
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load_thres: f32,
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extend_ratio: usize,
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buckets: Vec<Option<Pair>>,
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removed: Pair,
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size: usize, // 键值对数量
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capacity: usize, // 哈希表容量
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load_thres: f64, // 触发扩容的负载因子阈值
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extend_ratio: usize, // 扩容倍数
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buckets: Vec<Option<Pair>>, // 桶数组
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TOMBSTONE: Option<Pair>, // 删除标记
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}
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@ -31,10 +30,7 @@ impl HashMapOpenAddressing {
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load_thres: 2.0 / 3.0,
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extend_ratio: 2,
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buckets: vec![None; 4],
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removed: Pair {
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key: -1,
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val: "-1".to_string(),
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},
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TOMBSTONE: Some(Pair {key: -1, val: "-1".to_string()}),
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}
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}
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@ -44,27 +40,46 @@ impl HashMapOpenAddressing {
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}
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/* 负载因子 */
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fn load_factor(&self) -> f32 {
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self.size as f32 / self.capacity as f32
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fn load_factor(&self) -> f64 {
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self.size as f64 / self.capacity as f64
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}
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/* 搜索 key 对应的桶索引 */
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fn find_bucket(&mut self, key: i32) -> usize {
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let mut index = self.hash_func(key);
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let mut first_tombstone = -1;
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// 线性探测，当遇到空桶时跳出
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while self.buckets[index].is_some() {
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// 若遇到 key，返回对应的桶索引
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if self.buckets[index].as_ref().unwrap().key == key {
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// 若之前遇到了删除标记，则将建值对移动至该索引
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if first_tombstone != -1 {
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self.buckets[first_tombstone as usize] = self.buckets[index].take();
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self.buckets[index] = self.TOMBSTONE.clone();
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return first_tombstone as usize; // 返回移动后的桶索引
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}
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return index; // 返回桶索引
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}
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// 记录遇到的首个删除标记
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if first_tombstone == -1 && self.buckets[index] == self.TOMBSTONE {
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first_tombstone = index as i32;
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}
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// 计算桶索引，越过尾部返回头部
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index = (index + 1) % self.capacity;
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}
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// 若 key 不存在，则返回添加点的索引
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if first_tombstone == -1 { index } else { first_tombstone as usize }
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}
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/* 查询操作 */
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fn get(&self, key: i32) -> Option<&str> {
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let mut index = self.hash_func(key);
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let capacity = self.capacity;
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// 线性探测，从 index 开始向后遍历
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for _ in 0..capacity {
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// 计算桶索引，越过尾部返回头部
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let j = (index + 1) % capacity;
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match &self.buckets[j] {
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// 若遇到空桶，说明无此 key ，则返回 None
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None => return None,
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// 若遇到指定 key ，则返回对应 val
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Some(pair) if pair.key == key && pair != &self.removed => return Some(&pair.val),
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_ => index = j,
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fn get(&mut self, key: i32) -> Option<&str> {
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// 搜索 key 对应的桶索引
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let index = self.find_bucket(key);
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// 若找到键值对，则返回对应 val
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if self.buckets[index].is_some() && self.buckets[index] != self.TOMBSTONE {
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return self.buckets[index].as_ref().map(|pair| &pair.val as &str);
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}
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}
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// 若键值对不存在，则返回 null
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None
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}
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@ -74,56 +89,28 @@ impl HashMapOpenAddressing {
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if self.load_factor() > self.load_thres {
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self.extend();
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}
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let mut index = self.hash_func(key);
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let capacity = self.capacity;
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// 线性探测，从 index 开始向后遍历
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for _ in 0..capacity {
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//计算桶索引，越过尾部返回头部
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let j = (index + 1) % 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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match &mut self.buckets[j] {
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bucket @ &mut None | bucket @ &mut Some(Pair { key: -1, .. }) => {
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*bucket = Some(Pair { key, val });
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// 搜索 key 对应的桶索引
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let index = self.find_bucket(key);
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// 若找到键值对，则覆盖 val 并返回
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if self.buckets[index].is_some() && self.buckets[index] != self.TOMBSTONE {
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self.buckets[index].as_mut().unwrap().val = val;
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return;
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}
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// 若键值对不存在，则添加该键值对
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self.buckets[index] = Some(Pair { key, val });
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self.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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Some(pair) if pair.key == key => {
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pair.val = val;
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return;
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}
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_ => index = j,
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}
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}
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}
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/* 删除操作 */
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fn remove(&mut self, key: i32) {
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let mut index = self.hash_func(key);
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let capacity = self.capacity;
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// 遍历桶，从中删除键值对
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for _ in 0..capacity {
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let j = (index + 1) % capacity;
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match &mut self.buckets[j] {
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// 若遇到空桶，说明无此 key ，则直接返回
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None => return,
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// 若遇到指定 key ，则标记删除并返回
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Some(pair) if pair.key == key => {
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*pair = Pair {
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key: -1,
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val: "-1".to_string(),
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};
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// 搜索 key 对应的桶索引
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let index = self.find_bucket(key);
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// 若找到键值对，则用删除标记覆盖它
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if self.buckets[index].is_some() && self.buckets[index] != self.TOMBSTONE {
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self.buckets[index] = self.TOMBSTONE.clone();
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self.size -= 1;
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return;
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}
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_ => index = j,
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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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fn extend(&mut self) {
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@ -136,17 +123,24 @@ impl HashMapOpenAddressing {
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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 buckets_tmp {
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if let Some(pair) = pair {
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self.put(pair.key, pair.val);
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if pair.is_none() || pair == self.TOMBSTONE {
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continue;
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}
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let pair = pair.unwrap();
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self.put(pair.key, pair.val);
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}
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}
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/* 打印哈希表 */
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fn print(&self) {
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for pair in &self.buckets {
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match pair {
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Some(pair) => println!("{} -> {}", pair.key, pair.val),
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None => println!("None"),
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if pair.is_none() {
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println!("null");
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} else if pair == &self.TOMBSTONE {
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println!("TOMBSTONE");
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} else {
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let pair = pair.as_ref().unwrap();
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println!("{} -> {}", pair.key, pair.val);
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}
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}
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}
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@ -165,17 +159,17 @@ fn main() {
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hashmap.put(13276, "小法".to_string());
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hashmap.put(10583, "小鸭".to_string());
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println!("\n添加完成后,哈希表为\nKey -> Value");
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println!("\n添加完成后，哈希表为\nKey -> Value");
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hashmap.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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// 向哈希表输入键 key ，得到值 val
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let name = hashmap.get(13276).unwrap();
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println!("\n输入学号 13276 ,查询到姓名 {}", name);
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println!("\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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// 在哈希表中删除键值对 (key, val)
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hashmap.remove(16750);
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println!("\n删除 16750 后,哈希表为\nKey -> Value");
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println!("\n删除 16750 后，哈希表为\nKey -> Value");
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hashmap.print();
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}
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