removed trailing spaces

dynamic_programming/longest_arithmetic_subsequence.py

@@ -1,11 +1,11 @@
 """
-Longest Arithmetic Subsequence Problem: Given an array nums of integers, 
+Longest Arithmetic Subsequence Problem: Given an array nums of integers,
 return the length of the longest arithmetic subsequence in nums.
 
 Note that:
-- A subsequence is an array that can be derived from another array by 
+- A subsequence is an array that can be derived from another array by
 deleting some or no elements without changing the order of the remaining elements.
-- A sequence seq is arithmetic if seq[i + 1] - seq[i] are all the same value 
+- A sequence seq is arithmetic if seq[i + 1] - seq[i] are all the same value
 (for 0 <= i < seq.length - 1).
 """