题解 | #链表中环的入口结点#

    this.val = x;
    this.next = null;
}*/
function EntryNodeOfLoop(pHead)
{
    // write code here
    //初始化：快指针fast指向头结点，慢指针slow指向头结点;
    //让fast一次走两步，slow一次走一步，第一次相遇处，停止;
    //然后让fast指向头结点，slow原地不动，让fast，slow每次走一步，当再次相遇，就是入口结点
    let fast = pHead,slow = pHead
    while(fast && fast.next){
        fast = fast.next.next
        slow = slow.next
        if(fast === slow){
            let fast1 = pHead
            while(fast1 !== slow){
                fast1 = fast1.next
                slow = slow.next
            }
            return fast1
        }
    }
    return null
}
module.exports = {
    EntryNodeOfLoop : EntryNodeOfLoop
};