Intersection of Two Linked Lists

 1 class Solution {
 2 public:
 3     ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
 4         int la=0,lb=0;
 5         ListNode* pt=headA,*pa=headA,*pb=headB;
 6         while(pt!=NULL)
 7         {
 8             la++;
 9             pt=pt->next;
10         }
11         pt=headB;
12         while(pt!=NULL)
13         {
14             lb++;
15             pt=pt->next;
16         }
17         while(la>lb)
18         {
19             pa=pa->next;
20             la--;
21         }
22         while(lb>la)
23         {
24             pb=pb->next;
25             lb--;
26         }
27         while(pa!=pb)
28         {
29             pa=pa->next;
30             pb=pb->next;
31         }
32         return pa;
33     }
34 };