第八周作业

class Solution {    /**     * @param ListNode $headA     * @param ListNode $headB     * @return ListNode     */    function getIntersectionNode($headA, $headB) {        if($headA == null || $headB == null){            return null;        }        //先判断是否相交，不相交直接返回        if(!$this->isIntersect($headA, $headB)){            return null;        }        //若相交再找交叉点：分别遍历，并指向另一链表的头，这样遍历的长度相等        $cura = $headA;        $curb = $headB;        while($cura || $curb){            if($cura === $curb){                break;            }            $cura = $cura == null ? $headB : $cura->next;            $curb = $curb == null ? $headA : $curb->next;        }        return $cura;    }    //判断是否相交    function isIntersect($headA, $headB){        if($headB == null || $headB == null){            return false;        }        while($headA->next != null){            $headA = $headA->next;        }        while($headB->next != null){            $headB = $headB->next;        }        return $headA === $headB;    }}