输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。
<?phpclass ListNode{ ???var $val; ???var $next = NULL; ???function __construct($x){ ???????$this->val = $x; ???}}function Merge($pHead1, $pHead2) { ???if ($pHead1===null) { ???????return $pHead2; ???} ???if ($pHead2===null) { ???????return $pHead1; ???} ???if ($pHead1->val < $pHead2->val) { ???????$pHead1->next = Merge($pHead1->next, $pHead2); ???????return $pHead1; ???} ???$pHead2->next = Merge($pHead1, $pHead2->next); ???return $pHead2;}
用递归可以简化问题
PHP 合并2个链表
原文地址：https://www.cnblogs.com/mingzhanghui/p/9362844.html