psf/black code formatting (#1277)

dynamic_programming/coin_change.py

@@ -5,6 +5,8 @@ Can you determine number of ways of making change for n units using
 the given types of coins?
 https://www.hackerrank.com/challenges/coin-change/problem
 """
+
+
 def dp_count(S, m, n):
 
     # table[i] represents the number of ways to get to amount i
@@ -23,6 +25,6 @@ def dp_count(S, m, n):
     return table[n]
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     print(dp_count([1, 2, 3], 3, 4))  # answer 4
     print(dp_count([2, 5, 3, 6], 4, 10))  # answer 5