diff --git a/clone-graph/sora0319.java b/clone-graph/sora0319.java
new file mode 100644
index 000000000..a9e4d2214
--- /dev/null
+++ b/clone-graph/sora0319.java
@@ -0,0 +1,41 @@
+/*
+// Definition for a Node.
+class Node {
+    public int val;
+    public List<Node> neighbors;
+    public Node() {
+        val = 0;
+        neighbors = new ArrayList<Node>();
+    }
+    public Node(int _val) {
+        val = _val;
+        neighbors = new ArrayList<Node>();
+    }
+    public Node(int _val, ArrayList<Node> _neighbors) {
+        val = _val;
+        neighbors = _neighbors;
+    }
+}
+*/
+
+class Solution {
+    Map<Node, Node> visited = new HashMap<>();
+
+    public Node cloneGraph(Node node) {
+        if (node == null) return null;
+
+        if (visited.containsKey(node)) {
+            return visited.get(node);
+        }
+
+        Node clone = new Node(node.val);
+        visited.put(node, clone);
+
+        for (Node neighbor : node.neighbors) {
+            clone.neighbors.add(cloneGraph(neighbor));
+        }
+
+        return clone;
+    }
+}
+
diff --git a/longest-common-subsequence/sora0319.java b/longest-common-subsequence/sora0319.java
new file mode 100644
index 000000000..6ac97214e
--- /dev/null
+++ b/longest-common-subsequence/sora0319.java
@@ -0,0 +1,24 @@
+class Solution {
+    public int longestCommonSubsequence(String text1, String text2) {
+        int M = text1.length();
+        int N = text2.length();
+
+        int[][] dp = new int[M + 1][N + 1];
+
+        for (int i = 1; i <= M; i++) {
+            for (int j = 1; j <= N; j++) {
+                if (text1.charAt(i - 1) == text2.charAt(j - 1)) {
+                    // 문자가 일치하면 대각선 값 + 1
+                    dp[i][j] = dp[i - 1][j - 1] + 1;
+                } else {
+                    // 일치하지 않으면 왼쪽 또는 위쪽 값 중 큰 값 선택
+                    dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
+                }
+            }
+        }
+
+        // 최종 결과
+        return dp[M][N];
+    }
+}
+
diff --git a/longest-repeating-character-replacement/sora0319.java b/longest-repeating-character-replacement/sora0319.java
new file mode 100644
index 000000000..3eb08a7b4
--- /dev/null
+++ b/longest-repeating-character-replacement/sora0319.java
@@ -0,0 +1,29 @@
+import java.util.HashMap;
+import java.util.Map;
+
+public class Solution {
+    public int characterReplacement(String s, int k) {
+        int maxLen = 0;
+        int maxCount = 0;
+        Map<Character, Integer> counter = new HashMap<>();
+        int start = 0;
+
+        for (int end = 0; end < s.length(); end++) {
+            char endChar = s.charAt(end);
+            counter.put(endChar, counter.getOrDefault(endChar, 0) + 1);
+            maxCount = Math.max(maxCount, counter.get(endChar));
+
+            while (end - start + 1 - maxCount > k) {
+                char startChar = s.charAt(start);
+                counter.put(startChar, counter.get(startChar) - 1);
+                start++;
+            }
+
+            maxLen = Math.max(maxLen, end - start + 1);
+        }
+
+        return maxLen;
+    }
+}
+
+
diff --git a/palindromic-substrings/sora0319.java b/palindromic-substrings/sora0319.java
new file mode 100644
index 000000000..0d01265b1
--- /dev/null
+++ b/palindromic-substrings/sora0319.java
@@ -0,0 +1,19 @@
+class Solution {
+    public int countSubstrings(String s) {
+        int count = 0;
+
+        for (int i = 0; i < 2 * s.length() - 1; i++) {
+            int left = i / 2;
+            int right = left + i % 2;
+
+            while (left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {
+                count++;
+                left--;
+                right++;
+            }
+        }
+
+        return count;
+    }
+}
+
diff --git a/reverse-bits/sora0319.java b/reverse-bits/sora0319.java
new file mode 100644
index 000000000..91520bb35
--- /dev/null
+++ b/reverse-bits/sora0319.java
@@ -0,0 +1,14 @@
+public class Solution {
+    // you need treat n as an unsigned value
+    public int reverseBits(int n) {
+        String binary = String.format("%32s", Integer.toBinaryString(n)).replace(' ', '0');
+        System.out.println(binary);
+        
+        StringBuilder sb  = new StringBuilder(binary);
+        sb.reverse();
+        
+        
+        return Integer.parseUnsignedInt(sb.toString(),2);
+    }
+}
+