Map<String,List<String>> pickValueMap=DependentPickListValueController.GetDependentOptions('SObject','ControllingPickList','DependentPicklist');

/////////////////////////////////////////////////////////////////////////////////////////////////
public class DependentPickListValueController{
    public  DependentPickListValueController(){}
    public  static Map<String,List<String>> GetDependentOptions(String pObjName, String pControllingFieldName, String pDependentFieldName){
        Map<String,List<String>> objResults = new Map<String,List<String>>();
        //get the string to sobject global map
        Map<String,Schema.SObjectType> objGlobalMap = Schema.getGlobalDescribe();
        //get the type being dealt with
        Schema.SObjectType pType = objGlobalMap.get(pObjName);
        Map<String, Schema.SObjectField> objFieldMap = pType.getDescribe().fields.getMap();
        //get the control values   
        List<Schema.PicklistEntry> ctrl_ple = objFieldMap.get(pControllingFieldName).getDescribe().getPicklistValues();
        //get the dependent values
        List<Schema.PicklistEntry> dep_ple = objFieldMap.get(pDependentFieldName).getDescribe().getPicklistValues();
        //iterate through the values and get the ones valid for the controlling field name
        PickListUtils.Bitset objBitSet = new PickListUtils.Bitset();
        //set up the results
        for(Integer pControllingIndex=0; pControllingIndex<ctrl_ple.size(); pControllingIndex++){            
            //get the pointer to the entry
            Schema.PicklistEntry ctrl_entry = ctrl_ple[pControllingIndex];
            //get the label
            String pControllingLabel = ctrl_entry.getLabel();
            //create the entry with the label
            objResults.put(pControllingLabel,new List<String>());
        }
        //check the dependent values
        for(Integer pDependentIndex=0; pDependentIndex<dep_ple.size(); pDependentIndex++){            
            //get the pointer to the dependent index
            Schema.PicklistEntry dep_entry = dep_ple[pDependentIndex];
            //get the valid for
            String pEntryStructure = JSON.serialize(dep_entry);                
            PickListUtils.PicklistDetails objDepPLE = (PickListUtils.PicklistDetails)JSON.deserialize(pEntryStructure, PickListUtils.PicklistDetails.class);
            //iterate through the controlling values
            for(Integer pControllingIndex=0; pControllingIndex<ctrl_ple.size(); pControllingIndex++){    
                if (objBitSet.fitBit(objDepPLE.validFor,pControllingIndex)){                    
                    //get the label
                    String pControllingLabel = ctrl_ple[pControllingIndex].getLabel();
                    objResults.get(pControllingLabel).add(objDepPLE.label);
                }
            }
        } 
        return objResults;
    }
}
//////////////////////////////////////////////////////////////////

public class PickListUtils{
    public PickListUtils(){}
    public class PicklistDetails{
            public string active {get;set;}
            public string defaultValue {get;set;}
            public string label {get;set;}
            public string value {get;set;}
            public string validFor {get;set;}
            public PicklistDetails(){}
    }
    public class Bitset{
        public Map<String,Integer> AlphaNumCharCodes {get;set;}
        public Map<String, Integer> Base64CharCodes { get; set; }
        public Bitset(){
            findChacterCodes();
        }
        private void findChacterCodes(){
            AlphaNumCharCodes = new Map<String,Integer>{
                'A'=>65,'B'=>66,'C'=>67,'D'=>68,'E'=>69,'F'=>70,'G'=>71,'H'=>72,'I'=>73,'J'=>74,
                'K'=>75,'L'=>76,'M'=>77,'N'=>78,'O'=>79,'P'=>80,'Q'=>81,'R'=>82,'S'=>83,'T'=>84,
                'U'=>85,'V'=> 86,'W'=>87,'X'=>88,'Y'=>89,'Z'=>90    
            };
            Base64CharCodes = new Map<String, Integer>();
            //lower case
            Set<String> pUpperCase = AlphaNumCharCodes.keySet();
            for(String pKey : pUpperCase){
                //the difference between upper case and lower case is 32
                AlphaNumCharCodes.put(pKey.toLowerCase(),AlphaNumCharCodes.get(pKey)+32);
                //Base 64 alpha starts from 0 (The ascii charcodes started from 65)
                Base64CharCodes.put(pKey,AlphaNumCharCodes.get(pKey) - 65);
                Base64CharCodes.put(pKey.toLowerCase(),AlphaNumCharCodes.get(pKey) - (65) + 26);
            }
            //numerics
            for (Integer i=0; i<=9; i++){
                AlphaNumCharCodes.put(string.valueOf(i),i+48);
                //base 64 numeric starts from 52
                Base64CharCodes.put(string.valueOf(i), i + 52);
            }
        }
        public Boolean fitBit(String pValidFor,Integer n){
            //the list of bytes
            List<Integer> pBytes = new List<Integer>();
            //multiply by 6 since base 64 uses 6 bits
            Integer bytesBeingUsed = (pValidFor.length() * 6)/8;
            //will be used to hold the full decimal value
            Integer pFullValue = 0;
            //must be more than 1 byte
            if (bytesBeingUsed <= 1)
                return false;
            //calculate the target bit for comparison
            Integer bit = 7 - (Math.mod(n,8));
            //calculate the octet that has in the target bit
            Integer targetOctet = (bytesBeingUsed - 1) - (n >> bytesBeingUsed);
            //the number of bits to shift by until we find the bit to compare for true or false
            Integer shiftBits = (targetOctet * 8) + bit;
            //get the base64bytes
            for(Integer i=0;i<pValidFor.length();i++){
                //get current character value
                pBytes.Add((Base64CharCodes.get((pValidFor.Substring(i, i+1)))));
            }
            //calculate the full decimal value
            for (Integer i = 0; i < pBytes.size(); i++){
                Integer pShiftAmount = (pBytes.size()-(i+1))*6;//used to shift by a factor 6 bits to get the value
                pFullValue = pFullValue + (pBytes[i] << (pShiftAmount));
            }
            //shift to the bit which will dictate true or false
            Integer tBitVal = ((Integer)(Math.Pow(2, shiftBits)) & pFullValue) >> shiftBits;
            return  tBitVal == 1;
        }
     }  
 }