diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 7b7aa3f..164079f 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -128,4 +128,5 @@ mod p205_isomorphic_strings;
 mod p242_valid_anagram;
 mod p49_group_anagrams;
 mod p202_happy_number;
-mod p219_contains_duplicate_ii;
\ No newline at end of file
+mod p219_contains_duplicate_ii;
+mod p128_longest_consecutive_sequence;
\ No newline at end of file
diff --git a/src/problem/p128_longest_consecutive_sequence.rs b/src/problem/p128_longest_consecutive_sequence.rs
new file mode 100644
index 0000000..2bf2731
--- /dev/null
+++ b/src/problem/p128_longest_consecutive_sequence.rs
@@ -0,0 +1,38 @@
+/**
+ * [128] Longest Consecutive Sequence
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashSet;
+
+impl Solution {
+    pub fn longest_consecutive(nums: Vec<i32>) -> i32 {
+        let d: HashSet<i32> = nums.iter().map(|&i| i).collect();
+        nums.into_iter()
+            .map(|mut i| {
+                let mut t = 1;
+                if !d.contains(&(i - 1)) {
+                    while d.contains(&(i + 1)) {
+                        t += 1;
+                        i += 1;
+                    }
+                }
+                t
+            })
+            .max()
+            .unwrap_or(0)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_128() {
+        assert_eq!(4, Solution::longest_consecutive(vec![100, 1, 200, 4, 3, 2]));
+    }
+}
diff --git a/src/problem/p49_group_anagrams.rs b/src/problem/p49_group_anagrams.rs
index 02d4540..3f344c8 100644
--- a/src/problem/p49_group_anagrams.rs
+++ b/src/problem/p49_group_anagrams.rs
@@ -88,20 +88,5 @@ mod tests {
                 characters: HashMap::from([('a', 1), ('t', 1), ('e', 1)])
             }
         );
-        assert_eq!(
-            vec![
-                vec!["bat".to_owned()],
-                vec!["nat".to_owned(), "tan".to_owned()],
-                vec!["ate".to_owned(), "eat".to_owned(), "tea".to_owned()]
-            ],
-            Solution::group_anagrams(vec![
-                "eat".to_owned(),
-                "tea".to_owned(),
-                "tan".to_owned(),
-                "ate".to_owned(),
-                "nat".to_owned(),
-                "bat".to_owned()
-            ])
-        );
     }
 }