build

docs/chapter_hashing/hash_map.md

@@ -983,13 +983,11 @@ index = hash(key) % capacity
 
     /* 基于数组实现的哈希表 */
     class ArrayHashMap {
-        private var buckets: [Pair?] = []
+        private var buckets: [Pair?]
 
         init() {
             // 初始化数组，包含 100 个桶
-            for _ in 0 ..< 100 {
-                buckets.append(nil)
-            }
+            buckets = Array(repeating: nil, count: 100)
         }
 
         /* 哈希函数 */
@@ -1021,35 +1019,17 @@ index = hash(key) % capacity
 
         /* 获取所有键值对 */
         func pairSet() -> [Pair] {
-            var pairSet: [Pair] = []
-            for pair in buckets {
-                if let pair = pair {
-                    pairSet.append(pair)
-                }
-            }
-            return pairSet
+            buckets.compactMap { $0 }
         }
 
         /* 获取所有键 */
         func keySet() -> [Int] {
-            var keySet: [Int] = []
-            for pair in buckets {
-                if let pair = pair {
-                    keySet.append(pair.key)
-                }
-            }
-            return keySet
+            buckets.compactMap { $0?.key }
         }
 
         /* 获取所有值 */
         func valueSet() -> [String] {
-            var valueSet: [String] = []
-            for pair in buckets {
-                if let pair = pair {
-                    valueSet.append(pair.val)
-                }
-            }
-            return valueSet
+            buckets.compactMap { $0?.val }
         }
 
         /* 打印哈希表 */