/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */

/**
 * @param {ListNode} headA
 * @param {ListNode} headB
 * @return {ListNode}
 */

//  1、暴力解法
var getIntersectionNode = function(headA, headB) {
  var p1 = new ListNode()
  var p2 = new ListNode()
  p1 = headA
  p2 = headB

  if(!p1 && !p2){
    return p1
  }
  while(p1 != null){
    while(p2 != null){
      if(p2 == p1){
        return p1
      }else{
        p2 = p2.next
      }
      
    }
  p2 = headB
  p1 = p1.next 
  }

  return p1 
};


function getLen(p){
  var len = 0
   while(p != null){
    len ++
    p=p.next
  }
  return len
}

// 2、让长的链先走多出来的几步，然后同时走
var getIntersectionNode = function(headA, headB) {
  var len1 = 0
  var len2 = 0
  var p1 = new ListNode()
  var p2 = new ListNode()
  p1 = headA
  p2 = headB

  len1 = getLen(p1)
  len2 = getLen(p2)

  if(len1>len2){
    for(var i = 0;i < len1-len2;i++)
    p1=p1.next
  }else if(len1<len2){
    for(var i = 0;i < len2-len1;i++)
    p2=p2.next
  }

  while(p1 != p2){
    p1 = p1.next
    p2 = p2.next
  }

  return p1
 
};