题解 | #链表中环的入口结点#

/*function ListNode(x){
    this.val = x;
    this.next = null;
}*/
function EntryNodeOfLoop(pHead)
{
    // write code here
    if (pHead === null || pHead.next === null) {
        return null
    }
    let fast = pHead
    let slow = pHead
    while (fast) {
        slow = slow.next
        fast = fast.next.next

        if (slow === fast) {
            let p1 = pHead
            while (slow !== p1) {
                slow = slow.next
                p1 = p1.next
            }
            return p1
        }
    } 
    return null
}
module.exports = {
    EntryNodeOfLoop : EntryNodeOfLoop
};