/*
public class ListNode {
int val;
ListNode next = null;
ListNode(int val) {
this.val = val;
}
}*/
//时间复杂度:O(m+n) 空间复杂度O(1)
import java.util.*;
public class Solution {
public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
ListNode l1=pHead1;
ListNode l2 = pHead2;
while(l1!=l2){
l1=(l1==null)?pHead2:l1.next;
l2=(l2==null)?pHead1:l2.next;
}
return l1;
}
}