diff --git a/palindromic-substrings/s0ooo0k.java b/palindromic-substrings/s0ooo0k.java
new file mode 100644
index 000000000..5ad96b04d
--- /dev/null
+++ b/palindromic-substrings/s0ooo0k.java
@@ -0,0 +1,22 @@
+class Solution {
+    // 팰린드롬의 경우 양쪽이 같아야 하므로, 중심을 잡고 left, right로 늘려나가는 방식
+    public int countSubstrings(String s) {
+        int cnt = 0;
+
+        for(int i=0; i<s.length(); i++) {
+            cnt += palindrome(s, i, i);
+            cnt += palindrome(s, i, i+1);
+        }
+        return cnt;
+    }
+    public static int palindrome(final String s, int left, int right) {
+        int cnt = 0;
+        while(left>=0 && right < s.length() && s.charAt(left)==s.charAt(right)) {
+            cnt++;
+            left--;
+            right++;
+        }
+        return cnt;
+    }
+}
+
diff --git a/reverse-bits/s0ooo0k.java b/reverse-bits/s0ooo0k.java
new file mode 100644
index 000000000..38060f808
--- /dev/null
+++ b/reverse-bits/s0ooo0k.java
@@ -0,0 +1,12 @@
+class Solution {
+    public int reverseBits(int n) {
+        int result = 0;
+        for(int i = 0; i < 32; i++) {
+            result <<= 1;        
+            result |= (n & 1);   
+            n >>>= 1;            
+        }
+        return result;
+    }
+}
+