#include "iostream"
#include <TH1F.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TLorentzVector.h>
#include <TClonesArray.h>
#include "TFile.h"
#include "TTree.h"
#include "TTreeReader.h"
#include "TTreeReaderValue.h"
#include "TTreeReaderArray.h"
using namespace std;

void tests(){
   TFile *hfile = new TFile("unweighted.root","read");
   TTree *LHEF=(TTree*)hfile->Get("LHEF");
   auto nen = LHEF->GetEntries();
   LHEF->Show();
   TH1F *invm = new TH1F("H_invmass","GeV",100,0,150);
   TTreeReader reader("LHEF",hfile);
   TTreeReaderArray<double> ParticleM(reader,"Particle.M");
   long long e = 0;
   while (reader.Next())
   {
      for (size_t j=0; j< ParticleM.GetSize() ;j++)
      {
         Double_t k = ParticleM.At(j);
         invm->Fill(k);
      }
   }
   invm->Draw();
}

void mass()
{

   TFile *hfile = new TFile("unweighted.root","read");
   TTree *LHEF=(TTree*)hfile->Get("LHEF");

   LHEF->SetBranchStatus("*",0);
   LHEF->SetBranchStatus("Particle.M",1);
   LHEF->SetBranchStatus("Event_size",1);
   Long64_t nentries = LHEF->GetEntries();

   Int_t nParticle;
   Double_t Particle_M[9];

   LHEF->SetMakeClass(true);
   LHEF->SetBranchAddress("Particle",&nParticle);
   LHEF->SetBranchAddress("Particle.M",&(Particle_M[0]));
   TH1F *invm = new TH1F("H_invmass","GeV",100,0,150);
   Double_t k;
   for (Int_t i=0; i< LHEF->GetEntries();i++)
   {
      LHEF->GetEntry(i);
      for (Int_t j=0; j< nParticle ;j++)
      {
         k = Particle_M[j];
         cout<< Particle_M[j]<<endl;
         invm->Fill(k);
      }
      cout<<i<<endl;
   }
   invm->Draw();
   
}