diff --git a/104_maximum_depth_of_binary_tree/Makefile b/104_maximum_depth_of_binary_tree/Makefile
new file mode 100644
index 0000000..5a375a6
--- /dev/null
+++ b/104_maximum_depth_of_binary_tree/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test bst_depth.c
diff --git a/104_maximum_depth_of_binary_tree/bst_depth.c b/104_maximum_depth_of_binary_tree/bst_depth.c
new file mode 100644
index 0000000..d3e7085
--- /dev/null
+++ b/104_maximum_depth_of_binary_tree/bst_depth.c
@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct TreeNode {
+    int val;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+static int maxDepth(struct TreeNode* root)
+{
+    if (root == NULL) {
+        return 0;
+    }
+    int l = maxDepth(root->left) + 1;
+    int r = maxDepth(root->right) + 1;
+    return l > r ? l : r;
+}
+
+int main(void)
+{
+    printf("%d\n", maxDepth(NULL));
+    return 0;
+}
diff --git a/111_minimum_depth_of_binary_tree/Makefile b/111_minimum_depth_of_binary_tree/Makefile
new file mode 100644
index 0000000..5a375a6
--- /dev/null
+++ b/111_minimum_depth_of_binary_tree/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test bst_depth.c
diff --git a/111_minimum_depth_of_binary_tree/bst_depth.c b/111_minimum_depth_of_binary_tree/bst_depth.c
new file mode 100644
index 0000000..6a2626f
--- /dev/null
+++ b/111_minimum_depth_of_binary_tree/bst_depth.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct TreeNode {
+    int val;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+static int minDepth(struct TreeNode* root)
+{
+    if (root == NULL) {
+        return 0;
+    }
+
+    int l = minDepth(root->left) + 1;
+    int r = minDepth(root->right) + 1;
+    return l < r ? (l > 1 ? l : r) : (r > 1 ? r : l);
+}
+
+int main(void)
+{
+    struct TreeNode root, n1;
+    root.val = 1;
+    n1.val = 2;
+    root.left = &n1;
+    root.right = NULL;
+    n1.left = NULL;
+    n1.right = NULL;
+    printf("%d\n", minDepth(&root));
+    return 0;
+}