diff --git a/src/0409.longest-palindrome.409/solution.java b/src/0409.longest-palindrome.409/solution.java
new file mode 100644
index 00000000..fac1e1e5
--- /dev/null
+++ b/src/0409.longest-palindrome.409/solution.java
@@ -0,0 +1,22 @@
+class Solution {
+    public int longestPalindrome(String s) {
+        int[] counts = new int[52];
+        for(char c : s.toCharArray() ){
+            if(Character.isUpperCase(c)){
+                counts[c-'A']++;
+            }else{
+                counts[c-'a'+26]++;
+            }
+        }
+        boolean hasOdd = false;
+        int result = 0;
+        for(int count:counts){
+            if(count%2 == 1){
+                hasOdd = true;
+                count--;
+            }
+            result += count;
+        }
+        return result + (hasOdd?1:0);
+    }
+}
\ No newline at end of file