LC 160. Intersection of Two Linked Lists - better.txt

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
        
        HashSet<ListNode> nodeSet = new HashSet<>();

        while(headA != null)
        {
            nodeSet.add(headA);
            headA = headA.next;
        }

        while (headB != null) {
            if(nodeSet.contains(headB))
                return headB;
            headB = headB.next;
        }
        return null;
    }
}
// TC: O(m+n), SC: O(m)