Create swap_all_odd_and_even_bits.py

bit_manipulation/swap_all_odd_and_even_bits.py

@@ -0,0 +1,58 @@
+def show_bits(before: int, after: int) -> str:
+    """
+    >>> print(show_bits(0, 0xFFFF))
+        0: 00000000
+    65535: 1111111111111111
+    """
+    return f"{before:>5}: {before:08b}\n{after:>5}: {after:08b}"
+
+
+def swap_odd_even_bits(num: int) -> int:
+    """
+    1. We use bitwise AND operations to separate the even bits (0, 2, 4, 6, etc.) and
+       odd bits (1, 3, 5, 7, etc.) in the input number.
+    2. We then right-shift the even bits by 1 position and left-shift the odd bits by
+       1 position to swap them.
+    3. Finally, we combine the swapped even and odd bits using a bitwise OR operation
+       to obtain the final result.
+    >>> print(show_bits(0, swap_odd_even_bits(0)))
+        0: 00000000
+        0: 00000000
+    >>> print(show_bits(1, swap_odd_even_bits(1)))
+        1: 00000001
+        2: 00000010
+    >>> print(show_bits(2, swap_odd_even_bits(2)))
+        2: 00000010
+        1: 00000001
+    >>> print(show_bits(3, swap_odd_even_bits(3)))
+        3: 00000011
+        3: 00000011
+    >>> print(show_bits(4, swap_odd_even_bits(4)))
+        4: 00000100
+        8: 00001000
+    >>> print(show_bits(5, swap_odd_even_bits(5)))
+        5: 00000101
+       10: 00001010
+    >>> print(show_bits(6, swap_odd_even_bits(6)))
+        6: 00000110
+        9: 00001001
+    >>> print(show_bits(23, swap_odd_even_bits(23)))
+       23: 00010111
+       43: 00101011
+    """
+    # Get all even bits - 0xAAAAAAAA is a 32-bit number with all even bits set to 1
+    even_bits = num & 0xAAAAAAAA
+
+    # Get all odd bits - 0x55555555 is a 32-bit number with all odd bits set to 1
+    odd_bits = num & 0x55555555
+
+    # Right shift even bits and left shift odd bits and swap them
+    return even_bits >> 1 | odd_bits << 1
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+    for i in (-1, 0, 1, 2, 3, 4, 23, 24):
+        print(show_bits(i, swap_odd_even_bits(i)), "\n")