ARTS打卡：双指针的尝试

替换空格

<?php
class Solution {/*** @param String $s* @return String*/function replaceSpace($s) {$arr=str_split($s); //转化成数组foreach($arr as &$item){if($item==' '){//执行替换操作$item='%20';}}return implode('',$arr);    //数组转化成字符串返回}
}

反转链表

<?php
/*** Definition for a singly-linked list.* class ListNode {*     public $val = 0;*     public $next = null;*     function __construct($val = 0, $next = null) {*         $this->val = $val;*         $this->next = $next;*     }* }*/
class Solution {/*** @param ListNode $head* @return ListNode*/function reverseList($head) {$cur = $head;$pre = NULL;while($cur){$temp = $cur->next; $cur->next = $pre;$pre = $cur;$cur = $temp;}return $pre;}
}