diff --git a/clone-graph/Hyeri1ee.java b/clone-graph/Hyeri1ee.java
new file mode 100644
index 0000000000..f12d13c46a
--- /dev/null
+++ b/clone-graph/Hyeri1ee.java
@@ -0,0 +1,48 @@
+import java.util.*;
+/*
+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 {
+
+
+    //기존 node, 복사한 node
+    Map<Node, Node> visited = new HashMap<>();
+    public Node cloneGraph(Node node) {
+        if (node==null) return null;
+
+        if (visited.containsKey(node)){
+            return visited.get(node);
+        }
+
+        //없는 경우
+        Node newClone= new Node(node.val);
+        visited.put(node, newClone);
+
+        //이웃 복사
+        for(Node target : node.neighbors){
+            newClone.neighbors.add(cloneGraph(target));
+        }
+
+        return newClone;
+
+    }
+}
+
+
diff --git a/longest-common-subsequence/Hyeri1ee.java b/longest-common-subsequence/Hyeri1ee.java
new file mode 100644
index 0000000000..75a7378aa6
--- /dev/null
+++ b/longest-common-subsequence/Hyeri1ee.java
@@ -0,0 +1,33 @@
+import java.util.*;
+class Solution {
+    public int longestCommonSubsequence(String text1, String text2) {
+    
+        
+        //int longerlen= (text1.length() >= text2.length()) ? text1.length() : text2.length();
+        //int lesslen= (text1.length() <= text2.length()) ? text1.length() : text2.length();
+        int[][] dp = new int[text1.length()+1][text2.length()+1];
+
+        //String longertext= (text1.length() >= text2.length()) ? text1 : text2;
+        //String lesstext= (text1.length() <= text2.length()) ? text1 : text2;
+
+
+
+        for (int i = 1; i <=text1.length(); i++) {
+            for (int j = 1; j <=text2.length(); j++) {
+                //문자가 같으면
+                if (text1.charAt(i-1) == text2.charAt(j-1)){
+                    dp[i][j] = dp[i-1][j-1]+1; 
+                    //System.out.println("dp["+i+"]["+j+"]: "+ dp[i][j]);
+                }else{
+                    //문자가 다르면
+                    dp[i][j] = Math.max(dp[i-1][j], dp[i][j-1]);
+                    //System.out.println("dp["+i+"]["+j+"]: "+ dp[i][j]);
+                }
+            }
+        }
+
+
+        return dp[text1.length()][text2.length()];
+    }//end of method
+}
+
diff --git a/longest-repeating-character-replacement/Hyeri1ee.java b/longest-repeating-character-replacement/Hyeri1ee.java
new file mode 100644
index 0000000000..301f1ad3e1
--- /dev/null
+++ b/longest-repeating-character-replacement/Hyeri1ee.java
@@ -0,0 +1,61 @@
+class Solution {
+    //left,right
+
+    //right를 left에서부터 이동하면서 max (대체해야되는 alphabet 수) 갱신
+    //(right - left+ 1)  - 다수등장alphabet 개수 = 대체해야되는 alphabet 수
+    //대체해야되는 수 <= k 인 경우 완료
+    //"" > k 인 경우 left++
+    
+    //빈도수 저장용
+    int[] alpha = new int[26];
+    int answer =0 ;
+
+    public int characterReplacement(String s, int k) {
+        
+        //인덱스 정의 (초기값)
+        int left= 0;
+        int right= 0;
+
+
+
+        while(right < s.length()){
+            //현재 갱신된 right까지 빈도수 저장
+            //System.out.println("[right] : " + right);
+            //System.out.println("[left] : " + left);
+
+            alpha[s.charAt(right) - 'A']++;
+
+            int max = mostSeenFrequency(left, right, alpha); 
+
+            
+
+                while ((right-left + 1) - max > k) {
+                    alpha[s.charAt(left) - 'A']--;
+                    left++;
+                    max = mostSeenFrequency(left, right, alpha);
+                }
+
+                if (answer < right-left + 1){
+                    answer=right-left+1;
+                }
+                right++;
+
+                //System.out.println("[answer] : " + answer);
+               
+            
+        }//end of while
+
+        return answer;
+
+    }
+
+    private static int mostSeenFrequency(int left, int right, int[] alpha){
+        int max =0;
+        for(int i=0;i<26;i++){
+            if (max < alpha[i]) max=alpha[i];
+        }
+        return max;
+    }
+}
+
+
diff --git a/palindromic-substrings/Hyeri1ee.java b/palindromic-substrings/Hyeri1ee.java
new file mode 100644
index 0000000000..3a57e10032
--- /dev/null
+++ b/palindromic-substrings/Hyeri1ee.java
@@ -0,0 +1,49 @@
+class Solution {
+    //길이 1~s.length()까지 palindrome 함수 시도
+    int cnt=0; //
+
+
+    public int countSubstrings(String s) {
+
+        for(int len=1; len <= s.length();len++){//1~3
+            for(int idx =0; idx <= s.length()-len ; idx++){
+                //idx인덱스부터 len길이만큼의 문자열이 palindrome인지 판별
+                boolean result =  isPalindrome(s, idx, idx+len-1); //start: 시작 인덱스 , end: 끝 인덱스
+
+                if (result){
+                    cnt++;
+                }
+            }
+        }
+
+        return cnt;
+
+    }
+
+    private static boolean isPalindrome(String w, int start, int end){
+            if (start == end) return true;
+            //start!= end
+            int s = start;
+            int e = end;
+            while(s<= e){
+                if(e < start && s > end) return true;
+
+
+                //서로 값이 다른 경우
+                if (w.charAt(s) != w.charAt(e)){
+                    return false;
+                }
+
+                //서로 값이 같은 경우 continue;
+                s++;
+                e--;
+            }
+
+
+            return true;
+    }
+        
+   
+}
+
+
diff --git a/reverse-bits/Hyeri1ee.java b/reverse-bits/Hyeri1ee.java
new file mode 100644
index 0000000000..f9ffc93ce6
--- /dev/null
+++ b/reverse-bits/Hyeri1ee.java
@@ -0,0 +1,13 @@
+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;
+    }
+}
+