#include <iostream>
#include "TRandom.h"
#include "TMath.h" 

using namespace std;

void pi()
{
  // hit and miss method
  UInt_t hit = 0;

  for( UInt_t i = 0; i < 1e9; ++i ) {

    // two uniform random numbers for xy position on square
    Double_t x = gRandom->Uniform();
    Double_t y = gRandom->Uniform();

    // check if radius is within circle
    if( x*x + y*y <= 1 ) {
      ++hit;
    }

    if( i % 10000000 == 0 ) {
      Double_t pi = 4. * Double_t( hit ) / Double_t( i+1 );
      printf( "Event %d\tpi_mc = %10.8f\tpi = %10.8f\n", i, pi, TMath::Pi() );
    }
  }
}