Review Swift codes (#1150)

* feat(swift): review for chapter_computational_complexity

* feat(swift): review for chapter_data_structure

* feat(swift): review for chapter_array_and_linkedlist

* feat(swift): review for chapter_stack_and_queue

* feat(swift): review for chapter_hashing

* feat(swift): review for chapter_tree

* feat(swift): add codes for heap article

* feat(swift): review for chapter_heap

* feat(swift): review for chapter_graph

* feat(swift): review for chapter_searching

* feat(swift): review for chapter_sorting

* feat(swift): review for chapter_divide_and_conquer

* feat(swift): review for chapter_backtracking

* feat(swift): review for chapter_dynamic_programming

* feat(swift): review for chapter_greedy

* feat(swift): review for utils

* feat(swift): update ci tool

* feat(swift): trailing closure

* feat(swift): array init

* feat(swift): map index

codes/swift/chapter_hashing/hash_map_chaining.swift

@@ -30,7 +30,7 @@ class HashMapChaining {
 
     /* 负载因子 */
     func loadFactor() -> Double {
-        Double(size / capacity)
+        Double(size) / Double(capacity)
     }
 
     /* 查询操作 */
@@ -76,9 +76,10 @@ class HashMapChaining {
         for (pairIndex, pair) in bucket.enumerated() {
             if pair.key == key {
                 buckets[index].remove(at: pairIndex)
+                size -= 1
+                break
             }
         }
-        size -= 1
     }
 
     /* 扩容哈希表 */