Returns a dictionary that associates each position in the ranking with a list of integer 
        representations of the candidates ranked at that position.

def getReverseRankMap(self):
        """
        Returns a dictionary that associates each position in the ranking with a list of integer 
        representations of the candidates ranked at that position.
        """
        
        # We sort the candidates based on the number of incoming edges they have in the graph. If 
        # two candidates have the same number, we assume that they are tied.
        incEdgesMap = self.getIncEdgesMap()
        sortedKeys = sorted(incEdgesMap.keys(), reverse = True)
        reverseRankMap = dict()
        pos = 1
        for key in sortedKeys:
            cands = incEdgesMap[key]
            reverseRankMap[pos] = cands
            pos += 1
        return reverseRankMap