fix: check the rust codes and fix them (#653)

* fix: check the rust codes and fix it

* Update binary_tree_bfs.rs

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Co-authored-by: Yudong Jin <krahets@163.com>

codes/rust/chapter_searching/hashing_search.rs

@@ -34,7 +34,7 @@ pub fn main() {
     // 初始化哈希表
     let mut map = HashMap::new();
     for (i, num) in nums.iter().enumerate() {
-        map.insert(*num, i);
+        map.insert(*num, i); // key: 元素，value: 索引
     }
     let index = hashing_search_array(&map, target);
     println!("目标元素 3 的索引 = {}", index.unwrap());