Reverse Bits

Author: forest000014

reverse-bits/forest000014.java

@@ -0,0 +1,24 @@
+/*
+runtime 0 ms, beats 100.00%
+memory 41.47 MB, beats 90.14%
+
+time complexity: O(1)
+space complexity: O(1)
+
+i번째 bit를 구하고, 이를 ans(초기값 0)의 31-i번째 자리에 bitwise-OR 연산을 하여, bit 위치를 reverse 했습니다.
+*/
+
+public class Solution {
+    // you need treat n as an unsigned value
+    public int reverseBits(int n) {
+        int x = 1;
+        int ans = 0;
+        for (int i = 0; i < 32; i++) {
+            int bit = (x & n) >>> i;
+            bit <<= (31 - i);
+            ans |= bit;
+            x <<= 1;
+        }
+        return ans;
+    }
+}