Largest power of 2

bit_manipulation/largest_power_of_2.py

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+def largest_power_of_2(number: int) -> int:
+    """
+    returns the largest power of 2 that is less than
+    or equal to the given number
+    The way this works is that we shift the binary form of the number
+    to the right until we reach the last set bit
+    Using the number of times we had to shift to find the last set bit
+    we find the 2**(no of times shifted) which will be the ans
+    >>> largest_power_of_2(0)
+    0
+    >>> largest_power_of_2(1)
+    1
+    >>> largest_power_of_2(3)
+    2
+    >>> largest_power_of_2(15)
+    8
+    >>> largest_power_of_2(99)
+    64
+    >>> largest_power_of_2(178)
+    128
+    >>> largest_power_of_2(999999)
+    524288
+    """
+
+    if number == 0:
+        return 0
+    else:
+        last_set_bit = 0
+        while number:
+            last_set_bit += 1
+            number >>= 1
+        return 2 ** (last_set_bit - 1)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()