LeetCode160.相交链表

/**
 * 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) {
        ListNode end1 = headA,end2 = headB;
        int len1 = 0,len2 = 0;
        while(end1 != null) {
            end1 = end1.next;
            len1++;
        }
        while(end2 != null) {
            end2 = end2.next;
            len2++;
        }
        if(end1 != end2)
            return null;
        for(int i = 1;i <= Math.abs(len1-len2);i++) {
            if(len1 > len2)
                headA = headA.next;
            else 
                headB = headB.next;
        }
        while(headA != null && headB != null) {
            if(headA == headB)
                return headA;
            headA = headA.next;
            headB = headB.next;
        }
        return null;
    }
}