Fix Python code styles.

Update hash_map.

docs/chapter_array_and_linkedlist/array.md

@@ -144,7 +144,7 @@ elementAddr = firtstElementAddr + elementLength * elementIndex
 
     ```python title="array.py"
     """ 随机访问元素 """
-    def randomAccess(nums):
+    def random_access(nums):
         # 在区间 [0, len(nums)-1] 中随机抽取一个数字
         random_index = random.randint(0, len(nums) - 1)
         # 获取并返回随机元素

docs/chapter_computational_complexity/space_complexity.md

@@ -855,10 +855,10 @@ $$
 
     ```python title="space_complexity.py"
     """ 线性阶（递归实现） """
-    def linearRecur(n):
+    def linear_recur(n):
         print("递归 n =", n)
         if n == 1: return
-        linearRecur(n - 1)
+        linear_recur(n - 1)
     ```
 
 === "Go"

docs/chapter_hashing/hash_map.md

@@ -514,7 +514,7 @@ $$
         /* 删除操作 */
         void remove(int key) {
             int index = hashFunc(key);
-            // 置为空字符，代表删除
+            // 置为 nullptr ，代表删除
             bucket[index] = nullptr;
         }
     };
@@ -528,36 +528,36 @@ $$
         def __init__(self, key, val):
             self.key = key
             self.val = val
-    
+
     """ 基于数组简易实现的哈希表 """
     class ArrayHashMap:
         def __init__(self):
             # 初始化一个长度为 100 的桶（数组）
             self.bucket = [None] * 100
-    
+
         """ 哈希函数 """
-        def hashFunc(self, key):
+        def hash_func(self, key):
             index = key % 100
             return index
-    
+
         """ 查询操作 """
         def get(self, key):
-            index = self.hashFunc(key)
+            index = self.hash_func(key)
             pair = self.bucket[index]
             if pair is None:
                 return None
             return pair.val
-    
+
         """ 添加操作 """
         def put(self, key, val):
             pair = Entry(key, val)
-            index = self.hashFunc(key)
+            index = self.hash_func(key)
             self.bucket[index] = pair
-    
+
         """ 删除操作 """
         def remove(self, key):
-            index = self.hashFunc(key)
-            # 置为空字符，代表删除
+            index = self.hash_func(key)
+            # 置为 None ，代表删除
             self.bucket[index] = None
     ```
 
@@ -708,39 +708,6 @@ $$
             // 置为 null ，代表删除
             this.bucket[index] = null;
         }
-    
-        /* 获取所有键值对 */
-        public entries(): (Entry | null)[] {
-            let arr: (Entry | null)[] = [];
-            for (let i = 0; i < this.bucket.length; i++) {
-                if (this.bucket[i]) {
-                    arr.push(this.bucket[i]);
-                }
-            }
-            return arr;
-        }
-    
-        /* 获取所有键 */
-        public keys(): (number | undefined)[] {
-            let arr: (number | undefined)[] = [];
-            for (let i = 0; i < this.bucket.length; i++) {
-                if (this.bucket[i]) {
-                    arr.push(this.bucket[i]?.key);
-                }
-            }
-            return arr;
-        }
-    
-        /* 获取所有值 */
-        public values(): (string | undefined)[] {
-            let arr: (string | undefined)[] = [];
-            for (let i = 0; i < this.bucket.length; i++) {
-                if (this.bucket[i]) {
-                    arr.push(this.bucket[i]?.val);
-                }
-            }
-            return arr;
-        }
     }
     ```