#include "TTree.h"
#include "TFile.h"
#include "TRandom.h"

int main() {
  TTree *t = new TTree("t","t");
  float x;
  t->Branch("x",&x,"x/F");
  TFile *f = new TFile("test.root","RECREATE");
  TTree *tc = t->CloneTree();

  for(int j=0; j<10; ++j) {
    for(int i=0; i<50000; ++i) {
      x = gRandom->Gaus();
      t->Fill();
    }
    TTree *tempTree = t->CopyTree("x>3.5");
    tc->CopyEntries(tempTree);
    delete tempTree;
    t->Reset();
  }
  tc->Write();
  delete t;
  f->Write();
  f->Close();
  return 0;
}