diff --git a/longest-repeating-character-replacement/ICE0208.java b/longest-repeating-character-replacement/ICE0208.java
new file mode 100644
index 0000000000..f2539a5aa0
--- /dev/null
+++ b/longest-repeating-character-replacement/ICE0208.java
@@ -0,0 +1,25 @@
+class Solution {
+    public int characterReplacement(String s, int k) {
+        int[] frequency = new int[26];
+        int maxFrequency = 0;
+        int left = 0;
+        int maxLength = 0;
+
+        for (int right = 0; right < s.length(); right++) {
+            int index = s.charAt(right) - 'A';
+            frequency[index]++;
+
+            // maxFrequency 갱신
+            maxFrequency = Math.max(maxFrequency, frequency[index]);
+
+            // right - left + 1 - maxFrequency : 현재 위도우에서 maxFrequency를 제외한 개수
+            while (right - left + 1 - maxFrequency > k) {
+                frequency[s.charAt(left) - 'A']--;
+                left++;
+            }
+
+            maxLength = Math.max(maxLength, right - left + 1);
+        }
+        return maxLength;
+    }
+}
diff --git a/reverse-bits/ICE0208.java b/reverse-bits/ICE0208.java
new file mode 100644
index 0000000000..c23eeda693
--- /dev/null
+++ b/reverse-bits/ICE0208.java
@@ -0,0 +1,29 @@
+class Solution2 {
+    public int reverseBits(int n) {
+        int result = 0;
+
+        for (int i = 0; i < 32; i++) {
+            int lastBit = n & 1; // 가장 오른쪽 비트 추출
+
+            result <<= 1;        // 새 비트를 넣을 자리 확보
+            result |= lastBit;   // 추출한 비트를 오른쪽 끝에 추가
+
+            n >>>= 1;            // 처리한 비트를 버림.
+        }
+
+        return result;
+    }
+}
+
+class Solution {
+    public int reverseBits(int n) {
+        String binary = String.format("%32s", Integer.toBinaryString(n))
+                .replace(' ', '0');
+
+        String reversed = new StringBuilder(binary)
+                .reverse()
+                .toString();
+
+        return Integer.parseUnsignedInt(reversed, 2);
+    }
+}