diff --git a/docs/chapter_backtracking/backtracking_algorithm.md b/docs/chapter_backtracking/backtracking_algorithm.md
index 83a1bab9f..1405692bc 100644
--- a/docs/chapter_backtracking/backtracking_algorithm.md
+++ b/docs/chapter_backtracking/backtracking_algorithm.md
@@ -186,7 +186,18 @@ comments: true
 === "C"
 
     ```c title="preorder_traversal_i_compact.c"
-    [class]{}-[func]{preOrder}
+    /* 前序遍历：例题一 */
+    void preOrder(TreeNode *root) {
+        if (root == NULL) {
+            return;
+        }
+        if (root->val == 7) {
+            // 记录解
+            vectorPushback(res, root, sizeof(int));
+        }
+        preOrder(root->left);
+        preOrder(root->right);
+    }
     ```
 
 === "Zig"
diff --git a/docs/chapter_computational_complexity/iteration_and_recursion.md b/docs/chapter_computational_complexity/iteration_and_recursion.md
index 04a19fd67..7adc67549 100644
--- a/docs/chapter_computational_complexity/iteration_and_recursion.md
+++ b/docs/chapter_computational_complexity/iteration_and_recursion.md
@@ -1632,7 +1632,24 @@ status: new
 === "C"
 
     ```c title="recursion.c"
-    [class]{}-[func]{forLoopRecur}
+    /* 使用迭代模拟递归 */
+    int forLoopRecur(int n) {
+        int stack[1000]; // 借助一个大数组来模拟栈
+        int top = 0;
+        int res = 0;
+        // 递：递归调用
+        for (int i = n; i > 0; i--) {
+            // 通过“入栈操作”模拟“递”
+            stack[top++] = i;
+        }
+        // 归：返回结果
+        while (top >= 0) {
+            // 通过“出栈操作”模拟“归”
+            res += stack[top--];
+        }
+        // res = 1+2+3+...+n
+        return res;
+    }
     ```
 
 === "Zig"
diff --git a/docs/chapter_computational_complexity/space_complexity.md b/docs/chapter_computational_complexity/space_complexity.md
index 92dba0ce9..c37b7486f 100755
--- a/docs/chapter_computational_complexity/space_complexity.md
+++ b/docs/chapter_computational_complexity/space_complexity.md
@@ -1027,7 +1027,11 @@ $$
 === "Zig"
 
     ```zig title="space_complexity.zig"
-    [class]{}-[func]{function}
+    // 函数
+    fn function() i32 {
+        // 执行某些操作
+        return 0;
+    }
 
     // 常数阶
     fn constant(n: i32) void {
diff --git a/docs/chapter_hashing/hash_collision.md b/docs/chapter_hashing/hash_collision.md
index 381465310..395bcf91c 100644
--- a/docs/chapter_hashing/hash_collision.md
+++ b/docs/chapter_hashing/hash_collision.md
@@ -1152,7 +1152,7 @@ comments: true
     /* 链表节点 */
     struct node {
         Pair *pair;
-        struct Node *next;
+        struct node *next;
     };
 
     typedef struct node Node;
diff --git a/docs/chapter_hashing/hash_map.md b/docs/chapter_hashing/hash_map.md
index 6a6be2c48..66c911a6d 100755
--- a/docs/chapter_hashing/hash_map.md
+++ b/docs/chapter_hashing/hash_map.md
@@ -965,14 +965,18 @@ index = hash(key) % capacity
 
     ```swift title="array_hash_map.swift"
     /* 键值对 */
-    class Pair {
-        var key: Int
-        var val: String
+    class Pair: Equatable {
+        public var key: Int
+        public var val: String
 
-        init(key: Int, val: String) {
+        public init(key: Int, val: String) {
             self.key = key
             self.val = val
         }
+
+        public static func == (lhs: Pair, rhs: Pair) -> Bool {
+            lhs.key == rhs.key && lhs.val == rhs.val
+        }
     }
 
     /* 基于数组简易实现的哈希表 */