diff --git a/src/list.rs b/src/list.rs
new file mode 100644
index 0000000..26ce729
--- /dev/null
+++ b/src/list.rs
@@ -0,0 +1,33 @@
+// Definition for singly-linked list.
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub struct ListNode {
+  pub val: i32,
+  pub next: Option<Box<ListNode>>
+}
+
+impl ListNode {
+  #[inline]
+  fn new(val: i32) -> Self {
+    ListNode {
+      next: None,
+      val
+    }
+  }
+}
+
+pub fn make_list(arr: Vec<i32>) -> Option<Box<ListNode>> {
+    let mut head: Option<Box<ListNode>> = None;
+    let mut current = &mut head;
+
+    for &value in arr.iter() {
+        let new_node = Box::new(ListNode::new(value));
+        if current.is_none() {
+            *current = Some(new_node);
+        } else {
+            current.as_mut().unwrap().next = Some(new_node);
+            current = &mut current.as_mut().unwrap().next;
+        }
+    }
+
+    head
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 529a0f6..bd2ada0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,106 +1,57 @@
-use std::cmp::min;
-use std::collections::{BTreeSet, HashMap};
+use std::collections::HashSet;
+use crate::list::{make_list, ListNode};
 
 mod arr;
-
-#[derive(Debug)]
-struct Pair {
-    index: i32,
-    value: i32,
-}
-impl PartialEq for Pair {
-    fn eq(&self, other: &Pair) -> bool {
-        self.value == other.value && self.index == other.index
-    }
-}
-impl Eq for Pair {}
-impl PartialOrd for Pair {
-    fn partial_cmp(&self, other: &Pair) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-impl Ord for Pair {
-    fn cmp(&self, other: &Pair) -> std::cmp::Ordering {
-        if self.value == other.value {
-            other.index.cmp(&self.index)
-        } else {
-            other.value.cmp(&self.value)
-        }
-    }
-}
-
-impl Clone for Pair {
-    fn clone(&self) -> Self {
-        Pair {
-            index: self.index,
-            value: self.value,
-        }
-    }
-}
+mod list;
 
 struct Solution;
+
 impl Solution {
-    pub fn find_x_sum(nums: Vec<i32>, k: i32, x: i32) -> Vec<i32> {
-        let x = x as usize;
-        let mut tree: BTreeSet<Pair> = BTreeSet::new();
-        let mut dict: HashMap<i32, Pair> = HashMap::new();
-        let mut ans: Vec<i32> = vec![];
-        for i in 0..k as usize {
-            let mut pair = Pair {
-                index: nums[i],
-                value: 1,
-            };
-            if dict.contains_key(&nums[i]) {
-                let exist_pair = dict.get(&nums[i]).unwrap();
-                tree.remove(exist_pair);
-                pair.value += exist_pair.value;
+    pub fn modified_list(nums: Vec<i32>, head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
+        let mut set:HashSet<i32> = nums.into_iter().collect();
+        let mut cur = &head;
+        while let Some(node) = cur {
+            if set.contains(&node.val) {
+                cur = &node.next;
+            }else {
+                break;
             }
-            dict.insert(nums[i], pair.clone());
-            tree.insert(pair);
         }
-        ans.push(
-            tree.iter()
-                .take(min(tree.len(), x))
-                .fold(0, |last, cur| last + cur.value * cur.index),
-        );
-        for i in 0..nums.len() - k as usize {
-            let mut left_item = dict[&nums[i]].clone();
-            tree.remove(&left_item);
-            if left_item.value > 1 {
-                left_item.value -= 1;
-                dict.insert(nums[i], left_item.clone());
-                tree.insert(left_item);
+        let mut dummy_head = Box::new(ListNode{val:0, next: cur.clone()});
+        let mut last = &mut dummy_head.next;
+
+        // let mut cur = &mut(last.as_mut()?.next);
+        while let Some(node) = last {
+            if node.next.is_none() {break;}
+            if set.contains(&node.next.as_ref().as_ref()?.val) {
+                // this could be a shit!
+                let mut next_node = last.as_mut().unwrap().next.as_mut().unwrap().next.take();
+                let mut st = false;
+                while let Some(nd) = &next_node {
+                    if set.contains(&nd.as_ref().val) {
+                        next_node = next_node.as_mut().unwrap().next.take();
+                    }else {
+                        st = true;
+                        break;
+                    }
+                }
+                if !st {
+                    last.as_mut().unwrap().next = None;
+                }else {
+                    last.as_mut().unwrap().next = next_node;
+                }
+                last = &mut last.as_mut().unwrap().next;
             } else {
-                dict.remove(&nums[i]);
+                last = &mut last.as_mut().unwrap().next;
             }
-            if dict.contains_key(&nums[i + k as usize]) {
-                let mut pair = dict.get(&nums[i + k as usize]).unwrap().clone();
-                tree.remove(&pair);
-                pair.value += 1;
-                dict.insert(nums[i + k as usize], pair.clone());
-                tree.insert(pair);
-            } else {
-                let pair = Pair {
-                    index: nums[i + k as usize],
-                    value: 1,
-                };
-                dict.insert(nums[i + k as usize], pair.clone());
-                tree.insert(pair);
-            };
-            ans.push(
-                tree.iter()
-                    .take(min(tree.len(), x))
-                    .fold(0, |last, cur| last + cur.value * cur.index),
-            );
         }
-        ans
+        dummy_head.next
     }
 }
 
 fn main() {
-    let nums = vec![1, 1, 2, 2, 3, 4, 2, 3];
-    let k = 6;
-    let x = 2;
-    let result = Solution::find_x_sum(nums, k, x);
+    let nums = vec![1];
+    let head = make_list(vec![1,2,1,2,1,2]);
+    let result = Solution::modified_list(nums, head);
     println!("{:?}", result);
 }