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989. Add to Array-Form of Integer

Description

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.

 

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 <= 104
• 0 <= num[i] <= 9
• num does not contain any leading zeros except for the zero itself.
• 1 <= k <= 104

Solutions

• Java
• C++
• Python
• Go
• TypeScript
• RenderScript

• class Solution {
      public List<Integer> addToArrayForm(int[] num, int k) {
          int i = num.length - 1, carry = 0;
          LinkedList<Integer> ans = new LinkedList<>();
          while (i >= 0 || k > 0 || carry > 0) {
              carry += (i < 0 ? 0 : num[i--]) + k % 10;
              ans.addFirst(carry % 10);
              carry /= 10;
              k /= 10;
          }
          return ans;
      }
  }
  

• class Solution {
  public:
      vector<int> addToArrayForm(vector<int>& num, int k) {
          int i = num.size() - 1, carry = 0;
          vector<int> ans;
          for (; i >= 0 || k || carry; --i) {
              carry += (i < 0 ? 0 : num[i]) + k % 10;
              ans.push_back(carry % 10);
              carry /= 10;
              k /= 10;
          }
          reverse(ans.begin(), ans.end());
          return ans;
      }
  };
  

• class Solution:
      def addToArrayForm(self, num: List[int], k: int) -> List[int]:
          i, carry = len(num) - 1, 0
          ans = []
          while i >= 0 or k or carry:
              carry += (0 if i < 0 else num[i]) + (k % 10)
              carry, v = divmod(carry, 10)
              ans.append(v)
              k //= 10
              i -= 1
          return ans[::-1]
  
  

• func addToArrayForm(num []int, k int) []int {
  	i, carry := len(num)-1, 0
  	ans := []int{}
  	for ; i >= 0 || k > 0 || carry > 0; i-- {
  		if i >= 0 {
  			carry += num[i]
  		}
  		carry += k % 10
  		ans = append(ans, carry%10)
  		carry /= 10
  		k /= 10
  	}
  	for i, j := 0, len(ans)-1; i < j; i, j = i+1, j-1 {
  		ans[i], ans[j] = ans[j], ans[i]
  	}
  	return ans
  }
  

• function addToArrayForm(num: number[], k: number): number[] {
      let arr2 = [...String(k)].map(Number);
      let ans = [];
      let sum = 0;
      while (num.length || arr2.length || sum) {
          let a = num.pop() || 0,
              b = arr2.pop() || 0;
          sum += a + b;
          ans.unshift(sum % 10);
          sum = Math.floor(sum / 10);
      }
      return ans;
  }
  
  

• impl Solution {
      pub fn add_to_array_form(num: Vec<i32>, mut k: i32) -> Vec<i32> {
          let n = num.len();
          let mut res = vec![];
          let mut i = 0;
          let mut sum = 0;
          while i < n || sum != 0 || k != 0 {
              sum += num.get(n - i - 1).unwrap_or(&0);
              sum += k % 10;
              res.push(sum % 10);
  
              i += 1;
              k /= 10;
              sum /= 10;
          }
          res.reverse();
          res
      }
  }
  
  

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