Easy Bit Check Bit Manipulation
In plain English: Determine if a number is an exact power of 2 (like 1, 2, 4, 8, 16, ...).
A power of 2 has exactly one set bit. n & (n-1) clears it, leaving 0 — if not a power of 2, other bits remain.
Prompt
Check if a given positive integer n is a power of two.
Try to write it from scratch before scrolling down.
Solution
def is_power_of_two(n):
# exactly one set bit means power of 2; n-1 flips it and all lower bits
return n > 0 and (n & (n - 1)) == 0
# Test: is_power_of_two(16) == True
# Test: is_power_of_two(18) == False
# Test: is_power_of_two(1) == True