add reverse bits solution

Author: Tessa1217

reverse-bits/Tessa1217.java

@@ -0,0 +1,33 @@
+public class Solution {
+
+    // 비트 연산자 사용
+    public int reverseBits(int n) {
+        int answer = 0;
+        for (int i = 0; i < 32; i++) {
+            answer <<= 1;
+            answer |= (n & 1);
+            n >>>= 1;
+        }
+
+        return answer;
+    }
+
+    // you need treat n as an unsigned value
+    // O(1)
+    // public int reverseBits(int n) {
+
+    //     int answer = 0;
+
+    //     String binary = Integer.toBinaryString(n);
+
+    //     StringBuilder padded = new StringBuilder();
+    //     for (int i = 0; i < 32 - binary.length(); i++) {
+    //         padded.append('0');
+    //     }
+    //     padded.append(binary);
+
+    //     return (int) Long.parseLong(padded.reverse().toString(), 2);
+
+    // }
+}
+