add solution: reverse-bits

Author: dusunax

reverse-bits/dusunax.py

@@ -0,0 +1,41 @@
+'''
+# 190. Reverse Bits
+
+SolutionA: using bin() and int() to convert the types.
+SolutionB: using bitwise operations to reverse the bits.
+
+## Time and Space Complexity
+
+### SolutionA
+```
+TC: O(32) -> O(1)
+SC: O(1)
+```
+
+### SolutionB
+```
+TC: O(32) -> O(1)
+SC: O(1)
+```
+'''
+class Solution:
+    '''
+    SolutionA
+    - using bin() and int() to convert the number to binary and back to integer.
+    - use .zfill(32) ensures that the binary string is always 32 bits long.
+    '''
+    def reverseBitsA(self, n: int) -> int:
+        bit = bin(n)[2:].zfill(32)
+        return int(bit[::-1], 2)
+  
+    '''
+    SolutionB
+    - using bitwise operations to reverse the bits.
+    - iterate through the bits and reverse them.
+    '''
+    def reverseBitsB(self, n: int) -> int:
+        result = 0
+        for i in range(32):
+            result = (result << 1) | (n & 1) # shift the result to the left & add LSB of n
+            n >>= 1 # shift n to the right & remove previous LSB
+        return result