feat: add rust code for build_in_hash and hash_collision (#629)

* Create hash_map_chaining.rs

* Create hash_map_open_addressing.rs

* Create build_in_hash.rs

* Update Cargo.toml

codes/rust/chapter_hashing/hash_map_chaining.rs

@@ -0,0 +1,164 @@
+/*
+ * File: hash_map_chaining.rs
+ * Created Time: 2023-07-07
+ * Author: WSL0809 (wslzzy@outlook.com)
+ */
+
+#[derive(Clone)]
+/* 键值对 */
+struct Pair {
+    key: i32,
+    val: String,
+}
+
+/* 链式地址哈希表 */
+struct HashMapChaining {
+    size: i32,
+    capacity: i32,
+    load_thres: f32,
+    extend_ratio: i32,
+    buckets: Vec<Vec<Pair>>,
+}
+
+impl HashMapChaining {
+    /* 构造方法 */
+    fn new() -> Self {
+        Self {
+            size: 0,
+            capacity: 4,
+            load_thres: 2.0 / 3.0,
+            extend_ratio: 2,
+            buckets: vec![vec![]; 4],
+        }
+    }
+
+    /* 哈希函数 */
+    fn hash_func(&self, key: i32) -> usize {
+        key as usize % self.capacity as usize
+    }
+
+    /* 负载因子 */
+    fn load_factor(&self) -> f32 {
+        self.size as f32 / self.capacity as f32
+    }
+
+    /* 删除操作 */
+    fn remove(&mut self, key: i32) -> Option<String> {
+        let index = self.hash_func(key);
+        let bucket = &mut self.buckets[index];
+
+        // 遍历桶，从中删除键值对
+        for i in 0..bucket.len() {
+            if bucket[i].key == key {
+                let pair = bucket.remove(i);
+                self.size -= 1;
+                return Some(pair.val);
+            }
+        }
+
+        // 若未找到 key 则返回 None
+        None
+    }
+
+    /* 扩容哈希表 */
+    fn extend(&mut self) {
+        // 暂存原哈希表
+        let buckets_tmp = std::mem::replace(&mut self.buckets, vec![]);
+
+        // 初始化扩容后的新哈希表
+        self.capacity *= self.extend_ratio;
+        self.buckets = vec![Vec::new(); self.capacity as usize];
+        self.size = 0;
+
+        // 将键值对从原哈希表搬运至新哈希表
+        for bucket in buckets_tmp {
+            for pair in bucket {
+                self.put(pair.key, pair.val);
+            }
+        }
+    }
+
+    /* 打印哈希表 */
+    fn print(&self) {
+        for bucket in &self.buckets {
+            let mut res = Vec::new();
+            for pair in bucket {
+                res.push(format!("{} -> {}", pair.key, pair.val));
+            }
+            println!("{:?}", res);
+        }
+    }
+
+    /* 添加操作 */
+    fn put(&mut self, key: i32, val: String) {
+        // 当负载因子超过阈值时，执行扩容
+        if self.load_factor() > self.load_thres {
+            self.extend();
+        }
+
+        let index = self.hash_func(key);
+        let bucket = &mut self.buckets[index];
+
+        // 遍历桶，若遇到指定 key ，则更新对应 val 并返回
+        for pair in bucket {
+            if pair.key == key {
+                pair.val = val.clone();
+                return;
+            }
+        }
+        let bucket = &mut self.buckets[index];
+
+        // 若无该 key ，则将键值对添加至尾部
+        let pair = Pair {
+            key,
+            val: val.clone(),
+        };
+        bucket.push(pair);
+        self.size += 1;
+    }
+
+    /* 查询操作 */
+    fn get(&self, key: i32) -> Option<&str> {
+        let index = self.hash_func(key);
+        let bucket = &self.buckets[index];
+
+        // 遍历桶，若找到 key 则返回对应 val
+        for pair in bucket {
+            if pair.key == key {
+                return Some(&pair.val);
+            }
+        }
+
+        // 若未找到 key 则返回 None
+        None
+    }
+}
+
+/* Driver Code */
+pub fn main() {
+    /* 初始化哈希表 */
+    let mut map = HashMapChaining::new();
+
+    /* 添加操作 */
+    // 在哈希表中添加键值对 (key, value)
+    map.put(12836, "小哈".to_string());
+    map.put(15937, "小啰".to_string());
+    map.put(16750, "小算".to_string());
+    map.put(13276, "小法".to_string());
+    map.put(10583, "小鸭".to_string());
+    println!("\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
+    println!("\n输入学号 13276,查询到姓名 {}", match map.get(13276) {
+        Some(value) => value,
+        None => "Not a valid Key"
+    });
+
+    /* 删除操作 */
+    // 在哈希表中删除键值对 (key, value)
+    map.remove(12836);
+    println!("\n删除 12836 后，哈希表为\nKey -> Value");
+    map.print();
+}