regex c++

main.cpp

#include <iostream>
#include <string>
#include <set>
#include <stdio.h>

using namespace std;


bool FSM(char ch, int &S) {
  switch (S) {
    case 0:
      if (ch == 'd') {
        S = 1;
        return false;
      }
      cout << ch << " " << S << endl; 
      S = -1;
      return true;
    case 1:
      if (ch == 'o') {
        S = 2;
        return false;
      } 
      cout << ch << " " << S << endl;
      S = -1;
      return true;
    case 2:
      if (ch == ' ') {
        S = 3;
        return false;
      } 
      cout << ch << " " << S << endl;
      S = -1;
      return true;
    case 3:
      if (ch == 'u') {
        S = 4;
        return false;
      } 
      cout << ch << " " << S << endl;
      S = -1;
      return true;
    case 4:
      if (ch == 'n') {
        S = 5;
        return false;
      } 
      cout << ch << " " << S << endl;
      S = -1;
      return true;
    case 5:
      if (ch == 't') {
        S = 6;
        return false;
      } 
      cout << ch << endl;
      S = -1;
      return true;
    case 6:
      if (ch == 'i') {
        S = 7;
        return false;
      } 
      cout << ch << endl;
      S = -1;
      return true;
    case 7:
      if (ch == 'l') {
        S = 8;
        return false;
      } 
      cout << ch << endl;
      S = -1;
      return true;
    case 8:
      if (ch == ' ') {
        S = 9;
        return false;
      } 
      cout << ch << endl;
      S = -1;
      return true;
    case 9:
      if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')) {
        S = 10;
        return false;
      } 
      cout << ch << endl;
      S = -1;
      return true;
    case 10:
      if (
        (ch >= 'A' && ch <= 'Z') ||
        (ch >= 'a' && ch <= 'z') || 
        (ch >= '0' && ch <= '9')) {
        S = 10;
        return false;
      } 
      if (ch == '=') {
        S = 11;
        return false;
      } if (ch == '<') {
        S = 10;
        return false;
      } if (ch == '>') {
        S = 11;
        return false;
      }
      S = -1;
      return true;
    case 11:
      if (ch >= '0' && ch <= '9') {
        S = 12;
        return false;
      }
      S = -1;
      return true;
    case 12:
      if (ch >= '0' && ch <= '9') {
        S = 12;
        return false;
      }
      if (ch == ' ') {
        S = 13;
        return false;
      } 
      S = -1;
      return true;
    case 13:
      if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')) {
        S = 14;
        return false;
      } 
      S = -1;
      return true;
    case 14:
      if (
        (ch >= 'A' && ch <= 'Z') ||
        (ch >= 'a' && ch <= 'z') || 
        (ch >= '0' && ch <= '9')) {
        S = 14;
        return false;
      }
      if (ch == '=') {
        S = 15;
        return false;
      }
      S = -1;
      return true;
    case 15:
      if (ch >= '0' && ch <= '9') {
        S = 16;
        return false;
      }
      if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')) {
        S = 17;
        return false;
      }
      S = -1;
      return true;
    case 16:
      if (ch >= '0' && ch <= '9') {
        S = 16;
        return false;
      }
      if (ch == '+' || ch == '*' || ch == '-' || ch == '/') {
        S = 18;
        return false;
      }
      S = -1;
      return true;
    case 17:
      if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')) {
        S = 17;
        return false;
      }
      if (ch == '+' || ch == '*' || ch == '-' || ch == '/') {
        S = 18;
        return false;
      }
      S = -1;
      return true;
    case 18:
      if (ch == ' ') {
        S = 19;
        return false;
      }
      S = -1;
      return true;
    case 19:
      if (ch == 'l') {
        S = 20;
        return false;
      }
      S = -1;
      return true;
    case 20:
      if (ch == 'o') {
        S = 21;
        return false;
      }
      S = -1;
      return true;
    case 21:
      if (ch == 'o') {
        S = 22;
        return false;
      }
      S = -1;
      return true;
    case 22:
      if (ch == 'p') {
        S = 23;
        return false;
      }
      S = -1;
      return true;
    case 23:
      break;
    }
  }


int main() {
  int S = 0;
  string str;
  int Final = 23; // Множество конечных состояний автомата
  bool FEnter = false;
  while (getline(cin, str), str != "") {
      if (!FEnter)
          FEnter = true;
      else
          FSM('\n', S);
      for (auto i : str)
          if (FSM(i, S))
              break;
  }
  cout << S << endl;
  if (S == Final) // Проверяем, находится ли автомат в конечном состоянии
      cout << "Yes" << endl;
  else
      cout << "No" << endl;
  return 0;
}