Add to Array-Form of Integer Solution LeetCode

Solution Add to Array-Form of Integer LeetCode

For a non-negative integer X, the array-form of X is an array of its digits in left to right order.  For example, if X = 1231, then the array form is [1,2,3,1].

Given the array-form A of a non-negative integer X, return the array-form of the integer X+K.

Example 1:

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

Example 2:

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

Example 3:

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

Example 4:

Input: A = [9,9,9,9,9,9,9,9,9,9], K = 1
Output: [1,0,0,0,0,0,0,0,0,0,0]
Explanation: 9999999999 + 1 = 10000000000

Note:

  1. 1 <= A.length <= 10000
  2. 0 <= A[i] <= 9
  3. 0 <= K <= 10000
  4. If A.length > 1, then A[0] != 0

SOLUTION:

auto speedup = []() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	return nullptr;
}();

class Solution {
  public:
	vector<int> addToArrayForm(vector<int>& A, int K) {
		vector<int> ans;
		int j = A.size() - 1, carry = 0;
		while (K > 0 && j >= 0) {
			int curr = A[j--] + carry + K % 10;
			ans.push_back(curr % 10);
			carry = curr / 10;
			K /= 10;
		}
		while (j >= 0) {
			int curr = A[j--] + carry;
			ans.push_back(curr % 10);
			carry = curr / 10;
		}
		while (K > 0) {
			int curr = K % 10 + carry;
			ans.push_back(curr % 10);
			carry = curr / 10;
			K /= 10;
		}
		if (carry > 0) ans.push_back(carry);
		reverse(ans.begin(), ans.end());
		return ans;
	}
};

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