leetcode:add-two-numbers

• 问题

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

• leetcode类别

中等

• 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) {
        return $this->reverseList($this->getNode($l1, $l2));
    }

    function reverseList($list) {
        $prev = null;
        while($list !== null) {
            $node = new ListNode($list->val, null);
            $node->next = $prev;

            $prev = $node;
            $list = $list->next;
        }

        return $node;
    }

    function getNode($l1, $l2) {
        $prev = null;
        $plus = 0;
        
        while(true) {
            if ($l1 === null && $l2 === null && !$plus) {
                break;
            }

            $val = 0;
            if ($l1 !== null) {
                $val += $l1->val;
            }

            if ($l2 !== null) {
                $val += $l2->val;
            }

            $val += $plus;

            $plus = 0;
            if ($val > 9) {
                $val = $val % 10;
                $plus = 1;
            }
            
            $node = new ListNode($val, null);
            $node->next = $prev;

            $prev = $node;
            
            if ($l1 !== null) {
                $l1 = $l1->next;
            }

            if ($l2 !== null) {
                $l2 = $l2->next;
            }
        }

        return $node;
    }
}