diff --git a/reverse_linked_number.c b/reverse_linked_number.c
index 5515623..2443cfe 100644
--- a/reverse_linked_number.c
+++ b/reverse_linked_number.c
@@ -28,41 +28,28 @@ st_node *node_sum_r(int carry_up, st_node *p, st_node *q)
 
 st_node *node_sum(st_node *p, st_node *q)
 {
-    if (!p || !q) {
-        return 0;
-    }
+    if (!p || !q) return 0;
     return node_sum_r(0, p, q);
 }
 
 st_node *str_to_node(char *num)
 {
-    st_node *node = 0;
-    for (; *num; num++) {
-        st_node *new = node_alloc(*num - '0', 0);
-        new->next = node;
-        node = new;
-    }
-    return node;
+    if (!*num) return 0;
+    return node_alloc(*num - '0', str_to_node(num + 1));
 }
 
-int node_len(st_node *node)
+void node_show_r(st_node *node)
 {
-    int len = 0;
-    for (; node; node = node->next) len += 1;
-    return len;
+    if (!node) return;
+    node_show_r(node->next);
+    printf("%d", node->val);
+    return;
 }
 
 void node_show(st_node *node)
 {
-    int len = node_len(node);
-    char *buf = (char *)malloc(len + 1);
-    char *p = buf + len;
-    *p-- = 0;
-    for (; node; node = node->next) {
-        *p-- = node->val + '0';
-    }
-    printf("%s\n", buf);
-    free(buf);
+    node_show_r(node);
+    printf("\n");
     return;
 }