LeetCode 160. Intersection of Two Linked Lists

https://leetcode.com/problems/intersection-of-two-linked-lists/

	/**
	* 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 or !headB) return NULL;
	auto pA = headA;
	auto pB = headB;
	while(pA != pB){
	// move both 1 step
	pA = pA->next;
	pB = pB->next;
	// meeth same node
	if(pA == pB) break;
	// restart different list
	if(pA == NULL) pA = headB;
	if(pB == NULL) pB = headA;
	}
	return pA;
	}
	};

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