<div id="readability-page-1" class="page"><section><section><h3 id="category">알고리즘 / Solution</h3><ul><li> akasai
 </li><li>10월 13 화, 2020
 · 1 min read
 </li></ul><section data-v-fc5a9040=""><ul data-v-fc5a9040=""><li data-v-fc5a9040=""><a href="/tag/Algorithm/" data-v-fc5a9040="">
 Algorithm
 </a></li><li data-v-fc5a9040=""><a href="/tag/Leetcode/" data-v-fc5a9040="">
 Leetcode
 </a></li><li data-v-fc5a9040=""><a href="/tag/Typescript/" data-v-fc5a9040="">
 Typescript
 </a></li></ul></section></section><ins data-ad-client="ca-pub-7791595479585064" data-ad-slot="1631172523" data-ad-format="auto" data-full-width-responsive="true"></ins><section><article><img src="https://raw.githubusercontent.com/akasai/Algorithm-Solutions/master/Leetcode/leetcode-logo.png">
 
<blockquote>
<a href="https://leetcode.com/problems/add-two-numbers" target="_blank" rel="nofollow noopener noreferrer">String Compression</a>
</blockquote>
<hr>
<h2 id="how-to-solve">How To Solve</h2>
앞서 풀어봤던 List순회와는 조금 다른 내용이였다.
첫 시도는 재귀를 이용하여 접근했는데
잘못생각한 것 같아서 포인터를 이용한 방법으로 접근했다.
 
<h2 id="solution">Solution</h2>
<pre><code>function addTwoNumbers(l1: ListNode | null, l2: ListNode | null): ListNode | null {
 const answer = new ListNode()
 let head = answer
 let up = 0
 
 while(l1 || l2) {
 const sum = (l1?.val ?? 0) + (l2?.val ?? 0) + up

 up = Math.floor(sum / 10)
 head.val = sum % 10

 if (l1) l1 = l1.next
 if (l2) l2 = l2.next
 if (l1 || l2) {
 head.next = new ListNode()
 head = head.next
 }
 }
 
 if (up) head.next = new ListNode(up)
 return answer
}</code></pre>
<hr>
 
<h2 id="reference">Reference</h2>

<a href="https://github.com/akasai/Algorithm-Solutions/blob/master/Leetcode/Solution/26.Add_Two_Numbers.ts" target="_blank" rel="nofollow noopener noreferrer">Github</a>

</article></section><ins data-ad-client="ca-pub-7791595479585064" data-ad-slot="6759499833" data-ad-format="auto" data-full-width-responsive="true"></ins></section></div>

devlog.akasai

akasai

![](https://raw.githubusercontent.com/akasai/Algorithm-Solutions/master/Leetcode/leetcode-logo.png)
> [String Compression](https://leetcode.com/problems/add-two-numbers)
***
## How To Solve
앞서 풀어봤던 List순회와는 조금 다른 내용이였다.
첫 시도는 재귀를 이용하여 접근했는데
잘못생각한 것 같아서 포인터를 이용한 방법으로 접근했다.
## Solution
```typescript
function addTwoNumbers(l1: ListNode | null, l2: ListNode | null): ListNode | null {
  const answer = new ListNode()
  let head = answer
  let up = 0
  
  while(l1 || l2) {
    const sum = (l1?.val ?? 0) + (l2?.val ?? 0) + up
    up = Math.floor(sum / 10)
    head.val = sum % 10
    if (l1) l1 = l1.next
    if (l2) l2 = l2.next
    if (l1 || l2) {
      head.next = new ListNode()
      head = head.next
    }
  }
  
  if (up) head.next = new ListNode(up)
  return answer
}
```
***
## Reference
[Github](https://github.com/akasai/Algorithm-Solutions/blob/master/Leetcode/Solution/26.Add_Two_Numbers.ts)

[Leetcode] Add Two Numbers

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