一日一LeetCode 計畫

C# - Add Two Numbers

今天開始來實行一日一 LeetCode 計畫，除了讓自己更熟悉語言外，也想多練習更多的演算法
一開始也想不到要寫什麼side project
那麼就來刷刷 LeetCode 吧
從一開始註冊到現在也過了超久的(我就懶)
接下來會利用各種不同的語言寫同一個題目
目前計畫的有 C# , golang , php , typescript
希望能持續進步這些語言
話不多說我們就開始吧

題目為


You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example 1 :

Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.

Example 2 :

Input: l1 = [0], l2 = [0]
Output: [0]

Example 3 :

Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
Output: [8,9,9,9,0,0,0,1]

解法

  1. 看到這題目很直覺得知道是 LinkList 的題目，又有規律性，看起來就是一個可以用遞迴簡單處理的東西

  2. 實際解法

    /**
* Definition for singly-linked list.
* public class ListNode {
*     public int val;
*     public ListNode next;
*     public ListNode(int val=0, ListNode next=null) {
*         this.val = val;
*         this.next = next;
*     }
* }
*/
public class Solution {
    public ListNode AddTwoNumbers(ListNode l1, ListNode l2) {
            return Calculation(l1,l2,0);

        }

        private ListNode Calculation(ListNode l1, ListNode l2 , int add) {
            if(l1 == null && l2 == null && add ==0) {
                return null;
            }
            var result = (l1?.val ?? 0) + (l2?.val ?? 0) + add;
            var node_value = result % 10;
            var next_add_value = result /10;

            return new ListNode(node_value ,Calculation(l1?.next , l2?.next , next_add_value ) ) ;
        }

}

  3. 執行效能

C#  LeetCode 

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