Rename challenge directory

Author: iamminji

README.md

@@ -238,21 +238,21 @@
 
 | title      | code | solutions      |
 |------------------------------------------------------|------------|----------------|
-| [Arranging Coins](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3377/)      | [python](challenge/2020/july/Arranging_Coins.py)  | [solutions](challenge/2020/july/Arranging_Coins.md)|
-| [Binary Tree Level Order Traversal II](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3378/)      | [python](challenge/2020/july/Binary_Tree_Level_Order_Traversal_II.py)  | [solutions](challenge/2020/july/Binary_Tree_Level_Order_Traversal_II.md)|
-| [Prison Cells After N Days](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3379/)      | [python](challenge/2020/july/Prison_Cells_After_N_Days.py)  | [solutions](challenge/2020/july/Prison_Cells_After_N_Days.md)|
-| [Ugly Number II](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3380/)      | [python](challenge/2020/july/Ugly_Number_II.py)  | [solutions](challenge/2020/july/Ugly_Number_II.md)|
-| [Hamming Distance](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3381/)      | [python](challenge/2020/july/Hamming_Distance.py)  | [solutions](challenge/2020/july/Hamming_Distance.md)|
-| [Plus One](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3382/)      | [python](challenge/2020/july/Plus_One.py)  | [solutions](challenge/2020/july/Plus_One.md)|
-| [Island Perimeter](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3383/)      | [python](challenge/2020/july/Island_Perimeter.py)  | [solutions](challenge/2020/july/Island_Perimeter.md)|
-| [Flatten a Multilevel Doubly Linked List](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/545/week-2-july-8th-july-14th/3386/)      | [python](challenge/2020/july/Flatten_a_Multilevel_Doubly_Linked_List.py)  | [solutions](challenge/2020/july/Flatten_a_Multilevel_Doubly_Linked_List.md)|
-| [Same Tree](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/545/week-2-july-8th-july-14th/3389/)      | [python](challenge/2020/july/Same_Tree.py)  |  |
-| [3Sum](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/545/week-2-july-8th-july-14th/3384/)      | [python](challenge/2020/july/3Sum.py)  | [solutions](challenge/2020/july/3Sum.md)|
-| [Add Binary](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3395/)      | [python](challenge/2020/july/Add_Binary.py)  | [solution](challenge/2020/july/Add_Binary.md) |
-| [Subsets](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/545/week-2-july-8th-july-14th/3387/)      | [python](challenge/2020/july/Subsets.py)  |  |
-| [Reverse Words in a String](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3391/)      | [python](challenge/2020/july/Reverse_Words_in_a_String.py)  |  |
-| [Top K Frequent Elements](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3393/)      | [python](challenge/2020/july/Top_K_Frequent_Elements.py)  |  |
-| [Remove Linked List Elements](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3396/)      | [python](challenge/2020/july/Remove_Linked_List_Elements.py)  |  |
-| [Binary Tree Zigzag Level Order Traversal](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/547/week-4-july-22nd-july-28th/3398/)      | [python](challenge/2020/july/Binary_Tree_Zigzag_Level_Order_Traversal.py)  |  |
-| [Word Search](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3397/)      | [python](challenge/2020/july/Word_Search.py)  |  |
-| [All Paths From Source to Target](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/547/week-4-july-22nd-july-28th/3400/)      | [python](challenge/2020/july/All_Paths_From_Source_to_Target.py)  |  |
+| [Arranging Coins](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3377/)      | [python](challenge/2020/07/Arranging_Coins.py)  | [solutions](challenge/2020/07/Arranging_Coins.md)|
+| [Binary Tree Level Order Traversal II](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3378/)      | [python](challenge/2020/07/Binary_Tree_Level_Order_Traversal_II.py)  | [solutions](challenge/2020/07/Binary_Tree_Level_Order_Traversal_II.md)|
+| [Prison Cells After N Days](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3379/)      | [python](challenge/2020/07/Prison_Cells_After_N_Days.py)  | [solutions](challenge/2020/07/Prison_Cells_After_N_Days.md)|
+| [Ugly Number II](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3380/)      | [python](challenge/2020/07/Ugly_Number_II.py)  | [solutions](challenge/2020/07/Ugly_Number_II.md)|
+| [Hamming Distance](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3381/)      | [python](challenge/2020/07/Hamming_Distance.py)  | [solutions](challenge/2020/07/Hamming_Distance.md)|
+| [Plus One](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3382/)      | [python](challenge/2020/07/Plus_One.py)  | [solutions](challenge/2020/07/Plus_One.md)|
+| [Island Perimeter](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/544/week-1-july-1st-july-7th/3383/)      | [python](challenge/2020/07/Island_Perimeter.py)  | [solutions](challenge/2020/07/Island_Perimeter.md)|
+| [Flatten a Multilevel Doubly Linked List](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/545/week-2-july-8th-july-14th/3386/)      | [python](challenge/2020/07/Flatten_a_Multilevel_Doubly_Linked_List.py)  | [solutions](challenge/2020/07/Flatten_a_Multilevel_Doubly_Linked_List.md)|
+| [Same Tree](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/545/week-2-july-8th-july-14th/3389/)      | [python](challenge/2020/07/Same_Tree.py)  |  |
+| [3Sum](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/545/week-2-july-8th-july-14th/3384/)      | [python](challenge/2020/07/3Sum.py)  | [solutions](challenge/2020/07/3Sum.md)|
+| [Add Binary](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3395/)      | [python](challenge/2020/07/Add_Binary.py)  | [solution](challenge/2020/07/Add_Binary.md) |
+| [Subsets](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/545/week-2-july-8th-july-14th/3387/)      | [python](challenge/2020/07/Subsets.py)  |  |
+| [Reverse Words in a String](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3391/)      | [python](challenge/2020/07/Reverse_Words_in_a_String.py)  |  |
+| [Top K Frequent Elements](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3393/)      | [python](challenge/2020/07/Top_K_Frequent_Elements.py)  |  |
+| [Remove Linked List Elements](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3396/)      | [python](challenge/2020/07/Remove_Linked_List_Elements.py)  |  |
+| [Binary Tree Zigzag Level Order Traversal](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/547/week-4-july-22nd-july-28th/3398/)      | [python](challenge/2020/07/Binary_Tree_Zigzag_Level_Order_Traversal.py)  |  |
+| [Word Search](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/546/week-3-july-15th-july-21st/3397/)      | [python](challenge/2020/07/Word_Search.py)  |  |
+| [All Paths From Source to Target](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge/547/week-4-july-22nd-july-28th/3400/)      | [python](challenge/2020/07/All_Paths_From_Source_to_Target.py)  |  |