Trigger to call the Flow

DuplicateCheck.cls

trigger DuplicateCheck on Account (before insert,before update) {

  for(Account acc: Trigger.New)
  {
    Map<String, Object> params = new Map<String, Object>();
    params.put('varAccountName',acc.Name);
    params.put('varAccountId',acc.Id);
        
    Flow.Interview.DuplicateAccountCheck duplicateAccountCheck = new Flow.Interview.DuplicateAccountCheck(params);
    duplicateAccountCheck.start();
 
    // Obtain the results
    String returnValue = (String) DuplicateAccountCheck.getVariableValue('varReturnAccount');
    if(returnValue != null && returnValue != '')
      acc.Name.Adderror('Duplicate Account Found with the same Name: '+returnValue);
  }
}