@jinxonik / UniLecs #191

hospital_queue.cpp

#include <iostream>
#include <string>
#include <vector>
#include <list>

using std::cout;
using std::cin;
using std::string;
using std::vector;
using std::list;

list<int> hospital_list(const vector<string>& lst)
{
  list<int> result;
  auto middle = result.end();
  bool end_ins, inc_middle = true;
  std::size_t pos, count = 0;

  for (auto& s : lst) {
    end_ins = true;
    switch (s[0]) {
      case '*':
        end_ins = false;
        [[fallthrough]];  // to avoid doubling lines of next 'case'
      case '+':
        {
          int n = stoi(s.substr(1), &pos);  // pitient number
          if (pos != s.length()-1) { throw std::invalid_argument("extra chars"); }
          if (end_ins) { result.push_back(n); }  // '+'
          else { result.insert(std::next(middle), n); }  // '*'; 'next' is used because of 'insert_after' method absence
        }
        --count;  // compensation of ++count on 'fallthrough' to next 'case'
        [[fallthrough]];  // to avoid doubling ++middle !inc_middle lines :)
      case '-':
        if (!result.empty()) {
          ++count;
          if (inc_middle) { ++middle; }
          inc_middle = !inc_middle;
          break;
        } else { throw std::invalid_argument("empty queue"); }
      default:
        throw std::invalid_argument("wrong command");
    } // switch
  } // for

  if (result.size() > count) { result.resize(count); }  // to remove superfluous
  return result;
} // hospital_list

void print_list(const list<int>& lst)
{
  cout << "{ ";
  for (int n : lst) {
    cout << n << ' ';
  } // for
  cout << "}\n";
} // print_list

int main()
{
  print_list(hospital_list({ "+1", "+2", "-", "+3", "+4", "-", "-" }));
  print_list(hospital_list({ "+1", "+2", "*3", "-", "+4", "*5", "-", "-", "-", "-" }));
  return 0;
} // main

hospital_queue1.cpp

#include <iostream>
#include <string>
#include <vector>
#include <forward_list>

using std::cout;
using std::cin;
using std::string;
using std::vector;
using std::forward_list;

forward_list<int> hospital_list(const vector<string>& lst)
{
  forward_list<int> result;
  forward_list<int>::iterator middle, last, after;
  bool end_ins, inc_middle = true;
  std::size_t pos, count = 0;

  for (auto& s : lst) {
    end_ins = true;
    switch (s[0]) {
      case '*':
        end_ins = false;
        [[fallthrough]];  // to avoid doubling lines of next 'case'
      case '+':
        {
          int n = stoi(s.substr(1), &pos);  // pitient number
          if (pos != s.length()-1) { throw std::invalid_argument("extra chars"); }
          if (result.empty()) {
            result.push_front(n);
            middle = last = result.begin();
            inc_middle = !inc_middle;
            break;
          }
          else if (end_ins) { last = result.insert_after(last, n); }
          else { result.insert_after(middle, n); }
        }
        --count;  // compensation of ++count on 'fallthrough' to next 'case'
        [[fallthrough]];  // to avoid doubling ++middle !inc_middle lines :)
      case '-':
        if (!result.empty()) {
          ++count;
          if (inc_middle) { middle = std::next(middle); }
          inc_middle = !inc_middle;
          break;
        } else { throw std::invalid_argument("empty queue"); }
      default:
        throw std::invalid_argument("wrong command");
    } // switch
  } // for

  result.resize(count);  // to remove superfluous
  return result;
} // hospital_list

void print_list(const forward_list<int>& lst)
{
  cout << "{ ";
  for (int n : lst) {
    cout << n << ' ';
  } // for
  cout << "}\n";
} // print_list

int main()
{
  print_list(hospital_list({ "+1", "+2", "-", "+3", "+4", "-", "-" }));
  print_list(hospital_list({ "+1", "+2", "*3", "-", "+4", "*5", "-", "-", "-", "-" }));
  return 0;
} // main

hospital_queue2.cpp

#include <iostream>
#include <string>
#include <vector>
#include <deque>

using std::cout;
using std::cin;
using std::string;
using std::vector;
using std::deque;

deque<int> hospital_deque(const vector<string>& list)
{
  deque<int> result;
  std::size_t pos, count = 0;
  for (auto& s : list) {
    switch (s[0]) {
      case '+':
        result.push_back(stoi(s.substr(1), &pos));
        if (pos != s.length()-1) { throw std::invalid_argument("extra chars"); }
        break;
      case '*':
        result.insert(result.begin() + count + (result.size()+1)/2, stoi(s.substr(1), &pos));
        if (pos != s.length()-1) { throw std::invalid_argument("extra chars"); }
        break;
      case '-':
        if (!result.empty()) {
          count++;
          break;
        } else { throw std::invalid_argument("empty queue"); }
      default:
        throw std::invalid_argument("wrong command");
    } // switch
  } // for
  if (result.size() > count) { result.resize(count); }
  return result;
} // hospital_deque

void print_deque(const deque<int>& list)
{
  cout << "{ ";
  for (int n : list) {
    cout << n << ' ';
  } // for
  cout << "}\n";
} // print_deque

int main()
{
  print_deque(hospital_deque({ "+1", "+2", "-", "+3", "+4", "-", "-" }));
  print_deque(hospital_deque({ "+1", "+2", "*3", "-", "+4", "*5", "-", "-", "-", "-" }));
  return 0;
} // main