LeetCode_IntersectionofTwoLinkedLists.py

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

class Solution(object):
    def getLength(self, node):
        length = 0
        while node:
            length += 1
            node = node.next
        return length
    
    def getIntersectionNode(self, headA, headB):
        """
        :type head1, head1: ListNode
        :rtype: ListNode
        """
        if headA is None or headB is None: return None
        if headA.val == headB.val: return headA
        
        lengthA, lengthB = self.getLength(headA), self.getLength(headB)
        
        if lengthA > lengthB:
            longerNode, shorterNode = headA, headB
        else:
            longerNode, shorterNode = headB, headA
            
        difference = int(abs(lengthA - lengthB))
        for _ in range(difference):
            longerNode = longerNode.next
        
        while longerNode and shorterNode:
            if longerNode.val == shorterNode.val:
                return longerNode
            else:
                longerNode = longerNode.next
                shorterNode = shorterNode.next
        # End of while loop