diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index c4d82b4..f8a6f6d 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -39,4 +39,5 @@ mod p1686_stone_game_vi;
 mod p1690_stone_game_vii;
 mod p292_nim_game;
 mod p1696_jump_game_vi;
-mod lcp30_magic_tower;
\ No newline at end of file
+mod lcp30_magic_tower;
+mod p2641_cousins_in_binary_tree_ii;
\ No newline at end of file
diff --git a/src/problem/p2641_cousins_in_binary_tree_ii.rs b/src/problem/p2641_cousins_in_binary_tree_ii.rs
new file mode 100644
index 0000000..ad3ca3a
--- /dev/null
+++ b/src/problem/p2641_cousins_in_binary_tree_ii.rs
@@ -0,0 +1,97 @@
+/**
+ * [2641] Cousins in Binary Tree II
+ */
+pub struct Solution {}
+
+use crate::util::tree::{TreeNode, to_tree};
+
+// 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::rc::Rc;
+use std::cell::RefCell;
+impl Solution {
+    pub fn replace_value_in_tree(root: Option<Rc<RefCell<TreeNode>>>) -> Option<Rc<RefCell<TreeNode>>> {
+        let root = if let Some(r) = root {
+            r
+        } else {
+            return None;
+        };
+
+        let mut queue = Vec::new();
+        queue.push(Rc::clone(&root));
+
+        while !queue.is_empty() {
+            let mut next_queue = Vec::new();
+
+            let mut sum = 0;
+            for node in &queue {
+                if let Some(left) = &node.borrow().left {
+                    next_queue.push(Rc::clone(left));
+                    sum += left.borrow().val;
+                }
+
+                if let Some(right) = &node.borrow().right {
+                    next_queue.push(Rc::clone(right));
+                    sum += right.borrow().val;
+                }
+            }
+
+            for node in &queue {
+                let mut children = 0;
+                if let Some(left) = &node.borrow().left {
+                    children += left.borrow().val;
+                }
+
+                if let Some(right) = &node.borrow().right {
+                    children += right.borrow().val;
+                }
+
+                if let Some(left) = &node.borrow().left {
+                    left.borrow_mut().val = sum - children;
+                }
+
+                if let Some(right) = &node.borrow().right {
+                    right.borrow_mut().val = sum - children;
+                }
+            }
+
+            queue = next_queue;
+        }
+
+
+        root.borrow_mut().val = 0;
+        Some(root)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2641() {
+        assert_eq!(Solution::replace_value_in_tree(to_tree(
+            vec![Some(5),Some(4),Some(9),Some(1),Some(10),None,Some(7)])),
+                   to_tree(vec![Some(0),Some(0),Some(0),Some(7),Some(7),None,Some(11)]));
+    }
+}