203_Remove_Linked_List_Elements.py

# Remove all elements from a linked list of integers that have value val.
#
# Example
# Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
# Return: 1 --> 2 --> 3 --> 4 --> 5
#
# Credits:
#
# Tags: Linked List
# Difficulty: Easy


# Definition for singly-linked list.
class ListNode(object):
    def __init__(self, x):
        self.val = x
        self.next = None


class Solution(object):
    def removeElements(self, head, val):
        """
        :type head: ListNode
        :type val: int
        :rtype: ListNode
        """
        h = ListNode(0)
        h.next = head

        p, q = h, head
        while q:
            if q.val == val:
                q = q.next
                p.next = q
            else:
                p, q = q, q.next

        return h.next