tjut 5929

<pre name="code" class="html">#include <iostream>  #include <cstdio>  #include <cstring>  #include <queue>  using namespace std;  int a[450000];  deque<int> q;  int main()  {      int T;      scanf("%d",&T);      int ca=1;      while(T--)      {          int h=200001;          int t=h-1;          int type=1;          int n;          scanf("%d",&n);          char op[10];          q.clear();          int cnt=0;          printf("Case #%d:\n",ca++);          for(int i=0; i<n; i++)          {              scanf("%s",op);              int x;              if(op[0]=='P'&&op[1]=='U')              {                  scanf("%d",&x);                  if(type)                  {                      a[h]=x;                      if(!x)                      q.push_back(h);                      h++;                  }                  else                  {                      a[t]=x;                      if(!x)                      q.push_front(t);                      t--;                  }                  cnt++;              }              else if(op[0]=='P'&&op[1]=='O')              {                  if(cnt==0)                      continue;                  if(type)                  {                      if(a[h-1]==0)                          q.pop_back();                      h--;                  }                  else                  {                      if(a[t+1]==0)                          q.pop_front();                      t++;                  }                  cnt--;              }              else if(op[0]=='Q')              {                  int num=0;                  if(cnt==0)                  {                      cout<<"Invalid."<<endl;                  }                  else if(cnt==1)                  {                      cout<<a[h-1]<<endl;                  }                  else                  {                      if(type)                      {                          if(q.empty())                              num=cnt;                          else                          {                              num=q.front()==h-1?cnt-1:q.front()-t;                          }                      }                      else                      {                          if(q.empty())                              num=cnt;                          else                          {                              num=q.back()==t+1?cnt-1:h-q.back();                          }                        }                      if(num%2==0)                          cout<<"0"<<endl;                      else                          cout<<"1"<<endl;                  }              }              else              {                  type^=1;              }          }      }      return 0;  }