989.Add to Array-Form of Integer
===

###### tags: `Easy`,`Math`,`Array`

[989. Add to Array-Form of Integer](https://leetcode.com/problems/add-to-array-form-of-integer/)

### 題目描述

The **array-form** of an integer `num` is an array representing its digits in left to right order.

* For example, for `num = 1321`, the array form is `[1,3,2,1]`.

Given `num`, the **array-form** of an integer, and an integer `k`, return *the **array-form** of the integer* `num + k`.

### 範例

**Example 1:**

Input: num = [1,2,0,0], k = 34
Output: [1,2,3,4]
Explanation: 1200 + 34 = 1234

**Example 2:**

Input: num = [2,7,4], k = 181
Output: [4,5,5]
Explanation: 274 + 181 = 455

**Example 3:**

Input: num = [2,1,5], k = 806
Output: [1,0,2,1]
Explanation: 215 + 806 = 1021

**Constraints**:

* 1 <= `num.length` <= 10^4^
* 0 <= `num[i]` <= 9
* `num` does not contain any leading zeros except for the zero itself.
* 1 <= `k` <= 10^4^

### 解答
#### Python

class Solution:
    def addToArrayForm(self, num: List[int], k: int) -> List[int]:
        return list(map(int, str(int("".join(list(map(str, num)))) + k)))

> [name=Ron Chen][time=Wed, Feb 15, 2023]

#### Javascript

function addToArrayForm(num, k) {
  const result = [];
  let carry = 0;
  let i = num.length - 1;
  while (i >= 0 || k > 0) {
    const sum = (num[i] || 0) + (k % 10) + carry;
    result.unshift(sum % 10);
    carry = ~~(sum / 10);
    k = ~~(k / 10);
    i--;
  }

  if (carry) {
    result.unshift(carry);
  }

  return result;
}

> 用原始方法做一遍
> [name=Marsgoat][time=Wed, Feb 15, 2023]

### Reference

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