From 872cc825353530f5fb075fbc50f2112d3d49b079 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Tue, 26 May 2026 14:40:39 +0200
Subject: [PATCH] Avoid filling a vector just to count the bits

---
 DataFormats/Detectors/CTP/src/CTPRateFetcher.cxx | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/DataFormats/Detectors/CTP/src/CTPRateFetcher.cxx b/DataFormats/Detectors/CTP/src/CTPRateFetcher.cxx
index 5f31fe5741240..939203d168604 100644
--- a/DataFormats/Detectors/CTP/src/CTPRateFetcher.cxx
+++ b/DataFormats/Detectors/CTP/src/CTPRateFetcher.cxx
@@ -233,9 +233,7 @@ double CTPRateFetcher::pileUpCorrection(double triggerRate)
   if (mLHCIFdata.getFillNumber() == 0) {
     LOG(fatal) << "No filling" << std::endl;
   }
-  auto bfilling = mLHCIFdata.getBunchFilling();
-  std::vector<int> bcs = bfilling.getFilledBCs();
-  double nbc = bcs.size();
+  double nbc = mLHCIFdata.getBunchFilling().getPattern().count();
   double nTriggersPerFilledBC = triggerRate / nbc / constants::lhc::LHCRevFreq;
   double mu = -std::log(1 - nTriggersPerFilledBC);
   return mu * nbc * constants::lhc::LHCRevFreq;