add-to-array-form-of-integer.cpp

//question-989//

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
Example 4:

Input: num = [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
 

Constraints:

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


//solution//

class Solution {
public:
    vector<int> addToArrayForm(vector<int>& num, int k) {
       int carry=0;
       int n = num.size();
        vector<int> v;
        int i=n-1;
        while(i>=0 || k>0)
        {
            int a,b;
            if(i>=0)
            {
                a = num[i];
            }
            else
            {
                a = 0;
            }
            if(k>0)
            {
                b = k%10;
                k = k/10;
            }
            else
            {
                b = 0;
            }
            int sum = a+b+carry;
            carry = sum/10;
            sum = sum%10;
            v.push_back(sum);
            i--;
        }
        if(carry)
        {
            v.push_back(1);
        }
        reverse(v.begin(),v.end());
        return v;
    }
};