题目

对于非负整数 X 而言，X 的数组形式是每位数字按从左到右的顺序形成的数组。例如，如果 X = 1231，那么其数组形式为 [1,2,3,1]。

给定非负整数 X 的数组形式 A，返回整数 X+K 的数组形式。

示例 1：

输入：A = [1,2,0,0], K = 34
输出：[1,2,3,4]
解释：1200 + 34 = 1234

解释 2：

输入：A = [2,7,4], K = 181
输出：[4,5,5]
解释：274 + 181 = 455

示例 3：

输入：A = [2,1,5], K = 806
输出：[1,0,2,1]
解释：215 + 806 = 1021

示例 4：

输入：A = [9,9,9,9,9,9,9,9,9,9], K = 1
输出：[1,0,0,0,0,0,0,0,0,0,0]
解释：9999999999 + 1 = 10000000000

C++解法

#include <iostream>
#include <vector>
using namespace std;
class Solution {
public:
    vector<int> addToArrayForm(vector<int>& A, int K) {
        int num = K;
        int i = (int)A.size() - 1;
        int flag = 0;
        while (num > 0 || flag > 0) {
            int result = flag + (num % 10) + ((i >= 0) ? A[i] : 0);
            int actualNumber = result % 10;
            flag = (result >= 10);
            if (i >= 0) {
                A[i] = actualNumber;
            } else {
                A.insert(A.begin(), actualNumber);
            }
            num /= 10;
            i--;
        }
        return A;
    }
};
int main(int argc, const char * argv[]) {
    Solution solution;
    vector<int> vec;
    int num;
    vec = {1, 2, 0, 0};
    num = 181;
    auto result = solution.addToArrayForm(vec, num);
    for (auto item: result) cout << item; cout << endl;
    vec = {2, 7, 4};
    num = 181;
    result = solution.addToArrayForm(vec, num);
    for (auto item: result) cout << item; cout << endl;
    vec = {2, 1, 5};
    num = 806;
    result = solution.addToArrayForm(vec, num);
    for (auto item: result) cout << item; cout << endl;
    vec = {9,9,9,9,9,9,9,9,9,9};
    num = 1;
    result = solution.addToArrayForm(vec, num);
    for (auto item: result) cout << item; cout << endl;
    return 0;
}

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/add-to-array-form-of-integer