Prethodni i sljedeci datum (O)

#include <iostream>
using namespace std;

bool prestupna (int a)
{
     if (((a%4==0)&&(a%100!=0))||(a%400==0))
     return true;
     else
     return false;
}

main()
{
      int n, d[101], m[101], g[101];

      cin >> n;

      for (int i=0; i<n; i++)
          cin >> d[i] >> m[i] >> g[i];


      for (int i=0; i<n; i++)
      {
          cout << "Datum: " << d[i] << "." << m[i] << "." << g[i] << ". ";

          bool p = true;

          if (d[i]<1 || m[i]>12 || m[i]<1)
          p = false;

          switch(m[i])
          {
                      case 1: case 3: case 5: case 8: case 7: case 10: case 12:
                           if (d[i]>31)
                           p = false;

                      case 4: case 6: case 9: case 11:
                           if (d[i]>30)
                           p = false;

                      case 2:
                           if (prestupna(g[i])==true) { if (d[i]>29) p = false; }
                           else { if(d[i]>28) p = false; }
          }

          if (p==true)
          {
              // prethodni dan
              cout << "Prethodni: ";
              switch(m[i])
              {
                          case 12: case 5: case 7: case 10:
                               if (d[i]>1)
                               cout << d[i]-1 << "." << m[i] << "." << g[i] << ".";
                               else
                               cout << "30." << m[i]-1 << "." << g[i] << ".";
                          break;

                          case 2:
                               if (d[i]>1)
                               cout << d[i]-1 << "." << m[i] << "." << g[i] << ".";
                               else
                               cout << "31." << m[i]-1 << "." << g[i] << ".";
                          break;

                          case 4: case 6: case 9: case 11:
                               if (d[i]>1)
                               cout << d[i]-1 << "." << m[i] << "." << g[i] << ".";
                               else
                               cout << "31." << m[i]-1 << "." << g[i] << ".";
                          break;

                          case 3:
                               if(d[i]>1)
                                   cout << d[i]-1 << "." << m[i] << "." << g[i] << ".";
                               else
                               {
                                   if (prestupna(g[i])==true)
                                   cout << "29." << m[i]-1 << "." << g[i] << ".";
                                   else
                                   cout << "28." << m[i]-1 << "." << g[i] << ".";
                               }
                          break;

                          case 1:
                               if (d[i]>1)
                               cout << d[i]-1 << "." << m[i] << "." << g[i] << ".";
                               else
                               cout << "31.12." << g[i]-1 << ".";
                          break;
              }

              // naredni dan
              cout << " Naredni: ";
              switch(m[i])
              {
                          case 1: case 3: case 5: case 7: case 8: case 10:
                               if (d[i]<31)
                               cout << d[i]+1 << "." << m[i] << "." << g[i] << ".";
                               else
                               cout << "1." << m[i]+1 << "." << g[i] << ".";
                          break;

                          case 2:
                               if(prestupna(g[i])==true)
                               {
                                  if (d[i]<29)
                                  cout << d[i]+1 << "." << m[i] << "." << g[i] << ".";
                                  else
                                  cout << "1." << m[i]+1 << "." << g[i] << ".";
                               }
                               else
                               {
                                   if (d[i]<28)
                                   cout << d[i]+1 << "." << m[i] << "." << g[i] << ".";
                                    else
                                   cout << "1." << m[i]+1 << "." << g[i] << ".";
                               }
                          break;

                          case 4: case 6: case 9: case 11:
                               if (d[i]<30)
                               cout << d[i]+1 << "." << m[i] << "." << g[i] << ".";
                               else
                               cout << "1." << m[i]+1 << "." << g[i] << ".";
                          break;

                          case 12:
                               if (d[i]<31)
                               cout << d[i]+1 << "." << m[i] << "." << g[i] << ".";
                               else
                               cout << "1." << "1." << g[i]+1 << ".";
                          break;
              }
          }
          else cout << "neispravan";

          cout << endl;

      }

      system("PAUSE");
}