diff --git a/problems/0104.二叉树的最大深度.md b/problems/0104.二叉树的最大深度.md
index 0f93cb0f..607e195b 100644
--- a/problems/0104.二叉树的最大深度.md
+++ b/problems/0104.二叉树的最大深度.md
@@ -829,7 +829,42 @@ int maxDepth(struct TreeNode* root){
     return depth;
 }
 ```
-
+二叉树最大深度迭代——后序遍历实现
+```c
+int maxDepth(struct TreeNode *root)
+{
+    if(root == NULL)
+        return 0;
+    struct TreeNode *stack[10000] = {};
+    int top = -1;
+    struct TreeNode *p = root, *r = NULL; // r指向上一个被访问的结点
+    int depth = 0, maxDepth = -1;
+    while(p != NULL || top >= 0)
+    {
+        if(p != NULL)
+        {
+            stack[++top] = p;
+            depth++;
+            p = p->left;
+        }
+        else
+        {
+            p = stack[top];
+            if(p->right != NULL && p->right != r) // 右子树未被访问
+                p = p->right;
+            else
+            {
+                if(depth >= maxDepth) maxDepth = depth;
+                p = stack[top--];
+                depth--;
+                r = p;
+                p = NULL;
+            }
+        }
+    }
+    return maxDepth;
+}
+```
 ### Swift:
 
 104.二叉树的最大深度
diff --git a/problems/kamacoder/0055.右旋字符串.md b/problems/kamacoder/0055.右旋字符串.md
index 71371860..22be955f 100644
--- a/problems/kamacoder/0055.右旋字符串.md
+++ b/problems/kamacoder/0055.右旋字符串.md
@@ -253,6 +253,47 @@ func main(){
 ```
 
 
+### C：
+```C
+#include <stdio.h>
+#include <string.h>
+
+void reverse(char *s, int left, int right)
+{
+    while(left <= right)
+    {
+        char c = s[left];
+        s[left] = s[right];
+        s[right] = c;
+        left++;
+        right--;
+    }
+}
+
+void rightRotate(char *s, int k)
+{
+    int len = strlen(s);
+    // 先局部反转再整体反转
+    reverse(s, 0, len - k - 1);   // 反转前部分
+    reverse(s, len - k, len - 1); // 反转后部分：后k位
+    reverse(s, 0, len - 1);       // 整体反转
+}
+
+int main()
+{
+
+    int k;
+    scanf("%d", &k);
+    char s[10000];
+    scanf("%s", s);
+
+    rightRotate(s, k);
+    printf("%s\n", s);
+
+    return 0;
+}
+```
+
 ### JavaScript：