[DPG] Update k0s: add occupancy selection (#6252)

Author: njacazio

DPG/Tasks/AOTTrack/V0Cascades/perfK0sResolution.cxx

@@ -95,6 +95,8 @@ struct perfK0sResolution {
   Configurable<std::string> lutPath{"lutPath", "GLO/Param/MatLUT", "Path of the Lut parametrization"};
   Configurable<std::string> ccdburl{"ccdb-url", "http://alice-ccdb.cern.ch", "url of the ccdb repository"};
   Configurable<std::string> grpmagPath{"grpmagPath", "GLO/Config/GRPMagField", "CCDB path of the GRPMagField object"};
+  Configurable<int> minOccupancyCut{"minOccupancyCut", 1, "Minimum occupancy cut. Enabled if min < max"};
+  Configurable<int> maxOccupancyCut{"maxOccupancyCut", -1, "Maximum occupancy cut. Enabled if min < max"};
 
   int runNumber = -1;
 
@@ -421,6 +423,13 @@ struct perfK0sResolution {
                    soa::Filtered<aod::V0Datas> const& fullV0s,
                    PIDTracks const&)
   {
+    const int occupancy = collision.trackOccupancyInTimeRange();
+    if (minOccupancyCut < maxOccupancyCut) {
+      if (occupancy < minOccupancyCut || occupancy > maxOccupancyCut) {
+        return;
+      }
+    }
+
     rK0sResolution.fill(HIST("h1_stats"), 0.5);
     for (auto& v0 : fullV0s) {
       rK0sResolution.fill(HIST("h1_stats"), 1.5);