Intersection of Two Linked Lists

 1 ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
 2         //算法1：假设链表无环，对齐A,B链表
 3         ListNode * pa = headA;
 4         ListNode * pb = headB;
 5         int lengthA = 0, lengthB = 0;
 6         while ( pa )
 7         {
 8             pa = pa->next;
 9             lengthA++;
10         }
11         while ( pb )
12         {
13             pb = pb->next;
14             lengthB++;
15         }
16         
17         ListNode * pLong = NULL;
18         ListNode * pShort = NULL;
19         pLong = (lengthA >= lengthB)?headA:headB;
20         pShort = (lengthA < lengthB)?headA:headB;
21         //对齐两个链表
22         for ( int i = 0; i < abs(lengthA-lengthB); i++ )
23         {
24             pLong = pLong->next;
25         }
26         
27         while (pShort)
28         {
29             if (pShort == pLong)
30             {
31                 return pShort;
32             }
33             else
34             {
35                 pShort = pShort->next;
36                 pLong = pLong->next;
37             }
38         }
39         return NULL;
40     }