fix 3 questions to use get(v,0)

Author: rivkode

top-k-frequent-elements/rivkode.py

@@ -18,12 +18,7 @@ def topKFrequent(self, nums, k):
         dic = {}
 
         for v in nums:
-            if v in dic:
-                cur = dic[v]
-                cur += 1
-                dic[v] = cur
-            else:
-                dic[v] = 1
+            dic[v] = dic.get(v, 0) + 1
 
         reverse_desc = sorted(dic.items(), key=lambda item: item[1], reverse=True)