binary search C++11

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

using namespace std;

void input_barang();
void tampil_barang();
void cari_barang();

struct barang_baru
{
    string id;
    string nama_barang;
    string harga;
    string satuan;
    string jml_stok;
    string cari;
};

vector<barang_baru> rs;

int main()
{
    int pilihan;
    char menus;
    do
    {
        cout << " |====================|\n";
        cout << " | MENU PILIHAN |\n";
        cout << " |====================|\n";
        cout << " | |\n";
        cout << " | 1. Input Barang |\n";
        cout << " | |\n";
        cout << " | 2. Tampil Barang |\n";
        cout << " | |\n";
        cout << " | 3. Cari Barang |\n";
        cout << " |====================|\n";
        cout << "\nMasukkan pilihan anda : "; cin >> pilihan;
        switch (pilihan)
        {
        case 1:
            input_barang();
            break;
        case 2:
            tampil_barang();
            break;
        case 3:
            cari_barang();
            break;
        default:
            cout << "Menu Pilihan Tidak ada\n";

        }
        cout << "\nCoba Lagi[Y/T] : "; cin >>menus;
        menus = tolower(menus);
    } while (menus != 't');
}
void input_barang()
{
    int x, y;
    cout << "\n1. Input Barang\n\n";
    cout << "Masukkan Berapa Data Yang akan diinput : "; cin >> x;
    for (y = 0; y<x; y++)
    {
        barang_baru tmp;
        cout << "ID Barang : "; cin >> tmp.id;
        cout << "Nama Barang : "; cin >> tmp.nama_barang;
        cout << "Harga : "; cin >> tmp.harga;
        cout << "Satuan : "; cin >> tmp.satuan;
        cout << "Jumlah Stok : "; cin >> tmp.jml_stok;
        rs.push_back(tmp);
    }

    sort(rs.begin(), rs.end(), [](barang_baru& a, barang_baru& b){
        return a.id < b.id;
    });
}
void tampil_barang()
{
    cout << "Outputnya ";
    cout << "\nID \t Nama Barang \t\t Harga \t\t Satuan\t Jumlah Stok \n";
    for (auto&& item : rs)
    {
        cout << "\n" << item.id << "\t" << item.nama_barang << "\t\t" << item.harga << "\t\t" << item.satuan << "\t\t" << item.jml_stok;
    }
}

void cari_barang(){
    cout << "Masukkan id yang dicari : ";
    string id;
    cin >> id;
    size_t max_idx  = rs.size();
    size_t min_idx = 0;

    while (max_idx > min_idx){
        size_t midpoint = min_idx + ( (max_idx - min_idx) / 2);
        if (rs[midpoint].id < id){
            min_idx = midpoint + 1;
        }
        else {
            max_idx = midpoint;
        }

    }

    if (min_idx < rs.size() && rs[min_idx].id == id){
        auto item = rs[min_idx];
        cout << "\nID \t Nama Barang \t\t Harga \t\t Satuan\t Jumlah Stok \n";
        cout << "\n" << item.id << "\t" << item.nama_barang << "\t\t" << item.harga << "\t\t" << item.satuan << "\t\t" << item.jml_stok;
    }
    else {
        cout << "Item not found\n";
    }
}