An answer of https://gist.github.com/mtsmfm/4b8ffb53ffac055f5843

esm.cpp

#include <vector>
#include <string>
#include <numeric>
#include <iostream>
#include <algorithm>

constexpr size_t CHAIR_COUNTS = 8;
constexpr size_t OCCUPIED_STATE = 3;

void wait(std::vector<int>& chairs, size_t customer)
{
    for(size_t i = 0; i < chairs.size(); ++i)
    {
        chairs[i] = std::max(0, chairs[i] - 1);
    }
    const size_t vacant_chairs = std::count_if(chairs.begin(), chairs.end(), [&](int chair) { return chair == 0; });
    if(vacant_chairs < customer)
    {
        wait(chairs, customer);
    }
}

size_t chair_to_sit(const std::vector<int>& chairs, size_t customer)
{
    for(size_t i = 0; i < CHAIR_COUNTS; ++i)
    {
        std::vector<size_t> indeces;
        for(size_t j = i; j < i + customer; ++j)
        {
            indeces.push_back(j % CHAIR_COUNTS);
        }
        const auto found = std::all_of(indeces.begin(), indeces.end(), [&](int idx) { return chairs[idx] == 0; });
        if(found)
        {
            return i;
        }
    }
    return CHAIR_COUNTS;
}

void sit(std::vector<int>& chairs, size_t customer)
{
    size_t from = chair_to_sit(chairs, customer);
    while(0 < customer)
    {
        if(CHAIR_COUNTS <= from)
        {
            from = 0;
        }
        chairs[from] = OCCUPIED_STATE;
        ++from;
        --customer;
    }
}

std::string to_bit_string(const std::vector<int>& chairs)
{
    return std::accumulate(
            chairs.begin(), chairs.end(), std::string {},
            [&](const std::string& s, int chair) { return s + (chair == 0 ? "0" : "1"); });
}

std::string solve(const std::string& customers)
{
    std::vector<int> chairs(CHAIR_COUNTS, 0);
    for(size_t i = 0; i < customers.size(); ++i)
    {
        const auto n = customers[i] - '0';
        wait(chairs, n);
        sit(chairs, n);
    }
    return to_bit_string(chairs);
}

void test(const std::string& input, const std::string& expected)
{
    const auto actual = solve(input);
    std::cout << ( actual == expected ? "OK" : "***NG***" ) << std::endl;
}

void test_all()
{
    test("3316", "11111110");
    test("3342153", "11111111");
    test("8", "11111111");
    test("232624", "11110110");
    test("1", "10000000");
    test("224673432", "11111000");
    test("123464334", "11111110");
    test("44372332", "11111111");
    test("2344", "11111111");
    test("6448476233", "11111100");
    test("4345174644", "11111111");
    test("77743", "11111110");
    test("2136524281", "10000000");
    test("344373", "11100000");
    test("434226", "11111111");
    test("7433223", "11111110");
    test("2246534", "11110111");
    test("634", "11111110");
    test("2222", "11111100");
    test("2442343238", "11111111");
    test("7243344", "11111111");
    test("26147234", "10111111");
    test("34424", "10011111");
    test("6334", "11011111");
    test("3828342", "11011110");
    test("4431", "11110000");
    test("2843212125", "11111111");
    test("333336482", "11000000");
    test("374", "11110000");
    test("4382333", "11100111");
}

int main()
{
    test_all();
    return 0;
}