160.cpp

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
        if(!headA || !headB)
            return NULL;
        ListNode* curr1 = headA;
        ListNode* curr2 = headB;
        while(curr1!=curr2){
            curr1 = curr1->next;
            curr2 = curr2->next;
            if(curr1==curr2)
                return curr1;
            if(!curr1)
                curr1 = headB;
            if(!curr2)
                curr2 = headA;
        }
        return curr1;
    }
};