From 3ffc8976381bff452a0f2e2a59894777a0aa979d Mon Sep 17 00:00:00 2001
From: Tapas Singhal <98687345+Shocker-lov-t@users.noreply.github.com>
Date: Thu, 26 Oct 2023 22:26:37 +0530
Subject: [PATCH 1/4] Create find_previous_power_of_two.py

---
 .../find_previous_power_of_two.py             | 45 +++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 bit_manipulation/find_previous_power_of_two.py

diff --git a/bit_manipulation/find_previous_power_of_two.py b/bit_manipulation/find_previous_power_of_two.py
new file mode 100644
index 000000000000..afa49bbcfcab
--- /dev/null
+++ b/bit_manipulation/find_previous_power_of_two.py
@@ -0,0 +1,45 @@
+# https://stackoverflow.com/questions/1322510/given-an-integer-how-do-i-find-the-next-largest-power-of-two-using-bit-twiddlin
+
+def find_previous_power_of_two(number: int) -> int:
+    """
+    Find the largest power of two that is less than or equal to a given integer.
+
+    >>> find_previous_power_of_two(10)
+    8
+    >>> find_previous_power_of_two(16)
+    16
+    >>> find_previous_power_of_two(5)
+    4
+    >>> find_previous_power_of_two(1)
+    1
+    >>> find_previous_power_of_two(0)
+    0
+    >>> find_previous_power_of_two(-5)
+    Traceback (most recent call last):
+        ...
+    ValueError: Input must be a non-negative integer
+    >>> find_previous_power_of_two(10.5)
+    Traceback (most recent call last):
+        ...
+    TypeError: Input must be an integer
+    """
+
+    if not isinstance(number, int):
+        raise TypeError("Input must be an integer")
+
+    if number < 0:
+        raise ValueError("Input must be a non-negative integer")
+
+    if number == 0:
+        return 0
+
+    power = 1
+    while power <= number:
+        power <<= 1  # Equivalent to multiplying by 2
+
+    return power >> 1
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()

From 2970976ee70580c64987ec6128e9161b3623d475 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 26 Oct 2023 16:58:36 +0000
Subject: [PATCH 2/4] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 bit_manipulation/find_previous_power_of_two.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/bit_manipulation/find_previous_power_of_two.py b/bit_manipulation/find_previous_power_of_two.py
index afa49bbcfcab..8acbc38d71c3 100644
--- a/bit_manipulation/find_previous_power_of_two.py
+++ b/bit_manipulation/find_previous_power_of_two.py
@@ -1,5 +1,6 @@
 # https://stackoverflow.com/questions/1322510/given-an-integer-how-do-i-find-the-next-largest-power-of-two-using-bit-twiddlin
 
+
 def find_previous_power_of_two(number: int) -> int:
     """
     Find the largest power of two that is less than or equal to a given integer.
@@ -39,6 +40,7 @@ def find_previous_power_of_two(number: int) -> int:
 
     return power >> 1
 
+
 if __name__ == "__main__":
     import doctest
 

From a4a0b9d761e1dc1cc0fe1ee959c59276c88d9531 Mon Sep 17 00:00:00 2001
From: Tapas Singhal <98687345+Shocker-lov-t@users.noreply.github.com>
Date: Sun, 29 Oct 2023 14:48:03 +0530
Subject: [PATCH 3/4] Update find_previous_power_of_two.py

This change avoids the unnecessary left shift operation
---
 bit_manipulation/find_previous_power_of_two.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bit_manipulation/find_previous_power_of_two.py b/bit_manipulation/find_previous_power_of_two.py
index 8acbc38d71c3..42bde57c0054 100644
--- a/bit_manipulation/find_previous_power_of_two.py
+++ b/bit_manipulation/find_previous_power_of_two.py
@@ -38,7 +38,7 @@ def find_previous_power_of_two(number: int) -> int:
     while power <= number:
         power <<= 1  # Equivalent to multiplying by 2
 
-    return power >> 1
+    return power >> 1 if number > 1 else 1
 
 
 if __name__ == "__main__":

From 7b8af150b1312f9f028ead1aefeca7b1ae311073 Mon Sep 17 00:00:00 2001
From: Christian Clauss <cclauss@me.com>
Date: Sun, 29 Oct 2023 11:21:00 +0100
Subject: [PATCH 4/4] Update find_previous_power_of_two.py

---
 .../find_previous_power_of_two.py             | 27 ++++---------------
 1 file changed, 5 insertions(+), 22 deletions(-)

diff --git a/bit_manipulation/find_previous_power_of_two.py b/bit_manipulation/find_previous_power_of_two.py
index 42bde57c0054..8ac74ac98478 100644
--- a/bit_manipulation/find_previous_power_of_two.py
+++ b/bit_manipulation/find_previous_power_of_two.py
@@ -1,20 +1,10 @@
-# https://stackoverflow.com/questions/1322510/given-an-integer-how-do-i-find-the-next-largest-power-of-two-using-bit-twiddlin
-
-
 def find_previous_power_of_two(number: int) -> int:
     """
     Find the largest power of two that is less than or equal to a given integer.
+    https://stackoverflow.com/questions/1322510
 
-    >>> find_previous_power_of_two(10)
-    8
-    >>> find_previous_power_of_two(16)
-    16
-    >>> find_previous_power_of_two(5)
-    4
-    >>> find_previous_power_of_two(1)
-    1
-    >>> find_previous_power_of_two(0)
-    0
+    >>> [find_previous_power_of_two(i) for i in range(18)]
+    [0, 1, 2, 2, 4, 4, 4, 4, 8, 8, 8, 8, 8, 8, 8, 8, 16, 16]
     >>> find_previous_power_of_two(-5)
     Traceback (most recent call last):
         ...
@@ -22,22 +12,15 @@ def find_previous_power_of_two(number: int) -> int:
     >>> find_previous_power_of_two(10.5)
     Traceback (most recent call last):
         ...
-    TypeError: Input must be an integer
+    ValueError: Input must be a non-negative integer
     """
-
-    if not isinstance(number, int):
-        raise TypeError("Input must be an integer")
-
-    if number < 0:
+    if not isinstance(number, int) or number < 0:
         raise ValueError("Input must be a non-negative integer")
-
     if number == 0:
         return 0
-
     power = 1
     while power <= number:
         power <<= 1  # Equivalent to multiplying by 2
-
     return power >> 1 if number > 1 else 1