From c46cd473bb01bdbcdfab52d9e7f740148d218c09 Mon Sep 17 00:00:00 2001
From: BhaktiVagadia <bhakti.vagadia@gmail.com>
Date: Wed, 6 May 2026 20:15:07 +0530
Subject: [PATCH 1/2] add alternate harmonic series

---
 maths/series/alternate_harmonic_series.py | 50 +++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 maths/series/alternate_harmonic_series.py

diff --git a/maths/series/alternate_harmonic_series.py b/maths/series/alternate_harmonic_series.py
new file mode 100644
index 000000000000..ab9bd47f266e
--- /dev/null
+++ b/maths/series/alternate_harmonic_series.py
@@ -0,0 +1,50 @@
+def is_alternate_harmonic_series(series: list) -> bool:
+    """
+    checking whether the input series is alternate harmonic series or not
+    >>> is_alternate_harmonic_series([1, -1/2, 1/3, -1/4, 1/5])
+    True
+    >>> is_alternate_harmonic_series([2/5, -2/10, 2/15, -2/20, 2/25])
+    True
+    >>> is_alternate_harmonic_series([1, 1/2, 1/3, 1/4])
+    False
+    >>> is_alternate_harmonic_series([1, -1/2, 1/4, -1/8])
+    False
+    >>> is_alternate_harmonic_series(4)
+    Traceback (most recent call last):
+        ...
+    ValueError: Input series is not valid, valid series - [1, 2/3, 2]
+    >>> is_alternate_harmonic_series([])
+    Traceback (most recent call last):
+        ...
+    ValueError: Input list must be a non empty list
+    >>> is_alternate_harmonic_series([0])
+    Traceback (most recent call last):
+        ...
+    ValueError: Input series cannot have 0 as an element
+    >>> is_alternate_harmonic_series([1,2,0,6])
+    Traceback (most recent call last):
+        ...
+    ValueError: Input series cannot have 0 as an element
+    """
+    if not isinstance(series, list):
+        raise ValueError("Input series is not valid, valid series - [1, 2/3, 2]")
+    if len(series) == 0:
+        raise ValueError("Input list must be a non empty list")
+    if len(series) == 1 and series[0] != 0:
+        return True
+    receprocal= []
+    series_len = len(series)
+    for i in range(series_len):
+        if series[i] == 0:
+            raise ValueError("Input series cannot have 0 as an element")
+        receprocal.append(1 / series[i])
+    common_diff = abs(receprocal[1]) - abs(receprocal[0])
+    for index in range(2, series_len):
+        if abs(receprocal[index]) - abs(receprocal[index - 1]) != common_diff or receprocal[index]*receprocal[index-1] >= 0:
+            return False
+    return True
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
\ No newline at end of file

From cb7316eb7dc453aa42ba0c700009d3b5164334ca Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Wed, 6 May 2026 14:50:55 +0000
Subject: [PATCH 2/2] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 maths/series/alternate_harmonic_series.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/maths/series/alternate_harmonic_series.py b/maths/series/alternate_harmonic_series.py
index ab9bd47f266e..a887707d16fc 100644
--- a/maths/series/alternate_harmonic_series.py
+++ b/maths/series/alternate_harmonic_series.py
@@ -32,7 +32,7 @@ def is_alternate_harmonic_series(series: list) -> bool:
         raise ValueError("Input list must be a non empty list")
     if len(series) == 1 and series[0] != 0:
         return True
-    receprocal= []
+    receprocal = []
     series_len = len(series)
     for i in range(series_len):
         if series[i] == 0:
@@ -40,11 +40,15 @@ def is_alternate_harmonic_series(series: list) -> bool:
         receprocal.append(1 / series[i])
     common_diff = abs(receprocal[1]) - abs(receprocal[0])
     for index in range(2, series_len):
-        if abs(receprocal[index]) - abs(receprocal[index - 1]) != common_diff or receprocal[index]*receprocal[index-1] >= 0:
+        if (
+            abs(receprocal[index]) - abs(receprocal[index - 1]) != common_diff
+            or receprocal[index] * receprocal[index - 1] >= 0
+        ):
             return False
     return True
 
+
 if __name__ == "__main__":
     import doctest
 
-    doctest.testmod()
\ No newline at end of file
+    doctest.testmod()