989

989. Add to Array-Form of Integer (Easy)

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

Related Topics:
Array

Similar Questions:

• Add Two Numbers (Medium)
• Plus One (Easy)
• Add Binary (Easy)
• Add Strings (Easy)

Solution 1.

// OJ: https://leetcode.com/problems/add-to-array-form-of-integer/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    vector<int> addToArrayForm(vector<int>& A, int K) {
        int N = A.size(), carry = 0;
        vector<int> ans;
        for (int i = N - 1; i >= 0 || K || carry;) {
            if (K) {
                carry += K % 10;
                K /= 10;
            }
            if (i >= 0) carry += A[i--];
            ans.push_back(carry % 10);
            carry /= 10;
        }
        reverse(begin(ans), end(ans));
        return ans;
    }
};

Or use K as carry.

// OJ: https://leetcode.com/problems/add-to-array-form-of-integer/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    vector<int> addToArrayForm(vector<int>& A, int K) {
        int N = A.size();
        vector<int> ans;
        for (int i = N - 1; i >= 0 || K;) {
            if (i >= 0) K += A[i--];
            ans.push_back(K % 10);
            K /= 10;
        }
        reverse(begin(ans), end(ans));
        return ans;
    }
};