#include <fmt/ranges.h>

#include <vector>

using namespace std;

class Solution

{

public:

vector<int> plusOne(vector<int> &digits)

{

if (digits.empty()) {

return {1};

}

// Add 1 to the last digit

digits[digits.size() - 1] += 1;

if (digits[digits.size() - 1] < 10) {

return digits;

}

vector<int> sub = {digits.begin(), digits.end() - 1};

auto result = plusOne(sub);

result.push_back(0);

return result;

}

};

int main()

{

Solution sol;

// test case 1

vector<int> digits = {1, 2, 3};

fmt::print("Before: {}\n", fmt::join(sol.plusOne(digits), ", "));

// test case 2

digits = {4, 3, 2, 1};

fmt::print("Before: {}\n", fmt::join(sol.plusOne(digits), ", "));

// test case 3

digits = {9, 9, 9};

fmt::print("Before: {}\n", fmt::join(sol.plusOne(digits), ", "));

return 0;

}