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

/*
 * @lc app=leetcode id=989 lang=cpp
 *
 * [989] Add to Array-Form of Integer
 *
 * https://leetcode.com/problems/add-to-array-form-of-integer/description/
 *
 * algorithms
 * Easy (43.96%)
 * Total Accepted:    22.2K
 * Total Submissions: 50.4K
 * Testcase Example:  '[1,2,0,0]\n34'
 *
 * 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 <= A.length <= 10000
 * 0 <= A[i] <= 9
 * 0 <= K <= 10000
 * If A.length > 1, then A[0] != 0
 * 
 * 
 * 
 * 
 * 
 */
class Solution {
public:
    vector<int> addToArrayForm(vector<int>& A, int K) {
    	reverse(A.begin(), A.end());
    	int carry = 0, i = 0;
    	while(carry || K){
    		if(i == A.size())
    			A.push_back(K%10+carry);
    		else
    			A[i]+=(K%10+carry);
    		carry = A[i]/10;
    		A[i]%=10;
    		K/=10;
    		i++;
    	}
    	reverse(A.begin(), A.end());
    	return A;
    }
};