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题目

遍历第一个链表，使用Set保存每个节点的值，再遍历第二遍链表，看Set中是否有相同的值。

var getIntersectionNode = function(headA, headB) {
  if(!headA||!headB)return null;
  let cur1 = headA,cur2 = headB;
  const set = new Set();
  let ans = null;
  while(cur1){
    set.add(cur1);
    cur1 = cur1.next;
  }
  while(cur2){
    if(set.has(cur2)){
      ans = cur2;
      break;
    }
    cur2 = cur2.next;
  }
  return ans;
};

双指针

var getIntersectionNode = function(headA, headB) {
  if(!headA||!headB)return null;
  let cur1 = headA,cur2 = headB;
  while(cur1!==cur2){
    cur1 = cur1 === null ? headB : cur1.next;
    cur2 = cur2 === null ? headA : cur2.next;
  }
  return cur2;
};