diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 164079f..30785e6 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -129,4 +129,5 @@ mod p242_valid_anagram;
 mod p49_group_anagrams;
 mod p202_happy_number;
 mod p219_contains_duplicate_ii;
-mod p128_longest_consecutive_sequence;
\ No newline at end of file
+mod p128_longest_consecutive_sequence;
+mod p228_summary_ranges;
\ No newline at end of file
diff --git a/src/problem/p202_happy_number.rs b/src/problem/p202_happy_number.rs
index e2b33e0..a5d28aa 100644
--- a/src/problem/p202_happy_number.rs
+++ b/src/problem/p202_happy_number.rs
@@ -4,7 +4,7 @@
 pub struct Solution {}
 
 // submission codes start here
-use std::{collections::HashSet, ops::Add};
+use std::collections::HashSet;
 
 impl Solution {
     pub fn is_happy(n: i32) -> bool {
@@ -13,7 +13,6 @@ impl Solution {
         let mut n = Solution::calculate_square(n);
 
         while n != 1 {
-            dbg!(n);
             if s.contains(&n) {
                 return false;
             }
diff --git a/src/problem/p228_summary_ranges.rs b/src/problem/p228_summary_ranges.rs
new file mode 100644
index 0000000..b931932
--- /dev/null
+++ b/src/problem/p228_summary_ranges.rs
@@ -0,0 +1,54 @@
+/**
+ * [228] Summary Ranges
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn summary_ranges(nums: Vec<i32>) -> Vec<String> {
+        let mut result = vec![];
+
+        if nums.len() == 0 {
+            return result;
+        }
+
+        let mut begin = nums[0];
+        let mut end = nums[0];
+
+        for i in 1..nums.len() {
+            if nums[i] == end + 1 {
+                end += 1;
+            } else {
+                result.push(if begin == end {
+                    format!("{}", begin)
+                } else {
+                    format!("{}->{}", begin, end)
+                });
+
+                begin = nums[i];
+                end = nums[i];
+            }
+        }
+
+        result.push(if begin == end {
+            format!("{}", begin)
+        } else {
+            format!("{}->{}", begin, end)
+        });
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_228() {
+    }
+}