#include <algorithm>
#include <string>
#include <vector>

namespace {
    class Solution {
    public:
        std::vector<std::string> divideString(std::string s, int k, char fill) {
            std::vector<std::string> res;
            for (size_t i = 0; i < s.length(); i += k) {
                auto substr = s.substr(i, std::min<size_t>(k, s.length() - i));
                if (substr.length() < k) {
                    auto n = substr.length();
                    substr.resize(k);
                    std::fill_n(substr.begin() + n, k - n, fill);
                }
                res.emplace_back(substr);
            }
            return res;
        }
    };
}

#include <gtest/gtest.h>

TEST(P2138, 1) {
    std::string input = "abcdefghi";
    std::vector<std::string> expected = { "abc","def","ghi" };
    int k = 3;
    char fill = 'x';
    Solution s;
    auto res = s.divideString(input, k, fill);
    EXPECT_EQ(res, expected);
}

TEST(P2138, 2) {
    std::string input = "abcdefghij";
    std::vector<std::string> expected = { "abc","def","ghi","jxx" };
    int k = 3;
    char fill = 'x';
    Solution s;
    auto res = s.divideString(input, k, fill);
    EXPECT_EQ(res, expected);
}