实例:
输入:l1 = [2,4,3], l2 = [5,6,4]
输出:[7,0,8]
解释:342 + 465 = 807.
代码:
/**
* 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 $l1
* @param ListNode $l2
* @return ListNode
*/
function addTwoNumbers($l1, $l2) {
$obj = null;
$carry = 0;
do{
$val = $l1->val + $l2->val + $carry;
if($val < 10){
$carry = 0;
}else {
$carry = 1;
$val -= 10;
}
if($obj === null){
$obj = new ListNode($val);
$cur = $obj;
}else{
$cur->next = new ListNode($val);
$cur = $cur->next;
}
$l1 = $l1->next;
$l2 = $l2->next;
}while($l1 || $l2 || $carry);
return $obj;
}
}
优化:
/**
* 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 $l1
* @param ListNode $l2
* @return ListNode
*/
function addTwoNumbers($l1, $l2) {
$obj = null;
$carry = 0;
do{
$val = $l1->val + $l2->val + $carry;
if($val < 10){
$carry = 0;
}else {
$carry = 1;
$val -= 10;
}
$tmp_obj = new ListNode($val);
if($obj === null){
$obj = $tmp_obj;
}else{
$cur->next = $tmp_obj; // 将新的节点挂到当前节点之后
}
$cur = $tmp_obj; // 注意对象的clone和=的使用
$l1 = $l1->next;
$l2 = $l2->next;
}while($l1 || $l2 || $carry);
return $obj;
}
}
方法2种精简了方法1的写法,注意对象中clone和=的使用,以及链表中定位下一个节点的写法