diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index ef61b66..2ee46c9 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -142,4 +142,5 @@ mod p21_merge_two_sorted_lists;
 mod p104_maximum_depth_of_binary_tree;
 mod p100_same_tree;
 mod p226_invert_binary_tree;
-mod p101_symmetric_tree;
\ No newline at end of file
+mod p101_symmetric_tree;
+mod p114_flatten_binary_tree_to_linked_list;
\ No newline at end of file
diff --git a/src/problem/p114_flatten_binary_tree_to_linked_list.rs b/src/problem/p114_flatten_binary_tree_to_linked_list.rs
new file mode 100644
index 0000000..1251afa
--- /dev/null
+++ b/src/problem/p114_flatten_binary_tree_to_linked_list.rs
@@ -0,0 +1,77 @@
+/**
+ * [114] Flatten Binary Tree to Linked List
+ */
+pub struct Solution {}
+
+use crate::util::tree::{to_tree, TreeNode};
+
+// submission codes start here
+
+// Definition for a binary tree node.
+// #[derive(Debug, PartialEq, Eq)]
+// pub struct TreeNode {
+//   pub val: i32,
+//   pub left: Option<Rc<RefCell<TreeNode>>>,
+//   pub right: Option<Rc<RefCell<TreeNode>>>,
+// }
+//
+// impl TreeNode {
+//   #[inline]
+//   pub fn new(val: i32) -> Self {
+//     TreeNode {
+//       val,
+//       left: None,
+//       right: None
+//     }
+//   }
+// }
+use std::cell::RefCell;
+use std::rc::Rc;
+impl Solution {
+    fn flatten_tree(root: &Rc<RefCell<TreeNode>>) -> Rc<RefCell<TreeNode>> {
+        if (root.borrow().left.is_none() && root.borrow().right.is_none()) {
+            // 只有一个节点
+            return Rc::clone(root);
+        }
+
+        if root.borrow().right.is_some() {
+            let right = Rc::clone(&root.borrow().right.as_ref().unwrap());
+
+            if root.borrow().left.is_some() {
+                let left = Rc::clone(&root.borrow().left.as_ref().unwrap());
+                root.borrow_mut().right = Some(Rc::clone(&left));
+                root.borrow_mut().left = None;
+
+                let right_right = Self::flatten_tree(&left);
+                right_right.borrow_mut().right = Some(Rc::clone(&right));
+
+                return Self::flatten_tree(&right);
+            } else {
+                return Self::flatten_tree(&right);
+            }
+        } else {
+            let left = Rc::clone(&root.borrow().left.as_ref().unwrap());
+
+            root.borrow_mut().right = Some(Rc::clone(&left));
+            root.borrow_mut().left = None;
+
+            return Self::flatten_tree(&left);
+        }
+    }
+
+    pub fn flatten(root: &mut Option<Rc<RefCell<TreeNode>>>) {
+        if let Some(root) = root {
+            Self::flatten_tree(root);
+        }
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_114() {}
+}