Intersection of two linked lists

Hash Table Linked List Two Pointers

63.2% acceptance

Jan 13, 2026

16512

1491

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.

Solution

C++

Time O(n)

Space O(1)

LeetCode

solution.cpp

class Solution {
public:
  ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
    ListNode *a = headA, *b = headB;
    while (a != b) {
      a = a ? a->next : headB;
      b = b ? b->next : headA;
    }
    return a;
  }
};