[20200720] Solve July challenge question

Author: iamminji

README.md

@@ -238,3 +238,4 @@
 | [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)  |  |

challenge/2020/july/Remove_Linked_List_Elements.py

@@ -0,0 +1,26 @@
+# Definition for singly-linked list.
+class ListNode:
+    def __init__(self, val=0, next=None):
+        self.val = val
+        self.next = next
+
+
+class Solution:
+    def removeElements(self, head: ListNode, val: int) -> ListNode:
+
+        while head is not None and head.val == val:
+            head = head.next
+
+        if head is None:
+            return None
+
+        prev, dummy = head, head.next
+        while dummy is not None:
+            if dummy.val == val:
+                prev.next = dummy.next
+                dummy = dummy.next
+            else:
+                prev = prev.next
+                dummy = dummy.next
+
+        return head