題目： PHP 實現兩個鏈表的第一個公共結點

描述：
輸入兩個鏈表，找出它們的第一個公共結點。

<?php
/*class ListNode{var $val;var $next = NULL;function __construct($x){$this->val = $x;}
}*/
function FindFirstCommonNode($pHead1, $pHead2)
{if ($pHead1 == NULL || $pHead2 == NULL) {return NULL;}$arrData1 = array();$arrData2 = array();while ($pHead1 != NULL) {$arrData1[] = $pHead1;$pHead1 = $pHead1->next;}while ($pHead2 != NULL) {$arrData2[] = $pHead2;$pHead2 = $pHead2->next;}$pFirstCommon = NULL;while (!empty($arrData1) && !empty($arrData2)) {$pNode = array_pop($arrData1);$pNode2 = array_pop($arrData2);if ($pNode->val == $pNode2->val) {$pFirstCommon = $pNode;} else {break;}}return $pFirstCommon;
}