合并k个排序链表
采用分治法
<?php
class Node {public $next = null;public $val;public function __construct($val) {$this->val = $val;}
}
function mergeKLists($arrList) {$num = count($arrList);while ($num > 1) {$mid = intval(($num + 1) / 2);$arr = [];for ($i = 0; $i < $mid; $i ++) {$arr[] = mergeTwoLists($arrList[$i], $arrList[$i + $mid]);}$arrList = $arr;$num = count($arrList);}return $arrList[0];
}
function mergeTwoLists($node1, $node2) {$head = new Node(0);$p = $head;while ($node1 != null && $node2 != null) {if ($node1->val > $node2->val) {$p->next = $node2;$p = $node2;$node2 = $node2->next;} else {$p->next = $node1;$p = $node1;$node1 = $node1->next;}}if ($node1 != null) {$p->next = $node1;}if ($node2 != null) {$p->next = $node2;}return $head->next;
}
$node1 = new Node(1);
$node2 = new Node(4);
$node3 = new Node(5);
$node1->next = $node2;
$node2->next = $node3;
$node4 = new Node(1);
$node5 = new Node(3);
$node6 = new Node(4);
$node4->next = $node5;
$node5->next = $node6;
$node7 = new Node(2);
$node8 = new Node(6);
$node7->next = $node8;
$arr = [$node1,$node4,$node7];
$head = mergeKLists($arr);
while ($head != null) {print $head->val . "\n";$head = $head->next;
}