Updated longest_alternating_subsequence docstring

Author: FamALouiz

pydatastructs/linear_data_structures/algorithms.py

@@ -1885,7 +1885,7 @@ def longest_alternating_subsequence(array: OneDimensionalArray, **kwargs) -> int
     >>> arr = OneDimensionalArray(int, [1, 5, 4, 3, 2, 6, 7])
     >>> las = longest_alternating_subsequence(arr)
     >>> las
-    7
+    4
 
     References
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