Intersection of Two Linked Lists

Problem Statement
Given the heads of two singly linked lists, headA and headB, return the node at which the two lists intersect. If the two linked lists have no intersection at all, return null. The intersection is defined by reference (node identity), not by value, and the lists may have different lengths before intersecting. You must not modify the linked lists and the lists contain no cycles.[1][7]

Input/Output Examples

Example 1:

• Input: intersectVal = 8, listA = [4,1,8,4,5], listB = [5,6,1,8,4,5], skipA = 2, skipB = 3
  (Visual: listA starts with nodes 4→1→8→4→5; listB starts with 5→6→1→8→4→5; intersect at node 8)
• Output: intersected node with value 8 (the common node containing value 8)[7][1]

Example 2:

• Input: intersectVal = 2, listA = [1,9,1,2,4], listB = [3,2,4], skipA = 3, skipB = 1
  (Visual: listA: 1→9→1→2→4; listB: 3→2→4; intersect at node 2)
• Output: intersected node with value 2[1][7]

Example 3:

• Input: intersectVal = 0, listA = [2,6,4], listB = [1,5], skipA = 3, skipB = 2
  (No intersection)
• Output: null[7][1]

Constraints

• The number of nodes in listA is in the range [0, 10^4].
• The number of nodes in listB is in the range [0, 10^4].
• 1 <= Node.val <= 10^5 for each node.
• A node can only belong to one list at a time (no shared nodes before intersection).
• The linked lists will terminate (no cycles).
• You must solve it in O(m + n) time (where m and n are list lengths) and O(1) space ideally, though Hash Table (O(min(m,n)) space) is acceptable.[1][7]