def constructor(self, random, args):
        """Return a candidate solution for an ant colony optimization."""
        self._use_ants = True
        candidate = []
        while len(candidate) < len(self.weights) - 1:
            # Find feasible components
            feasible_components = []
            if len(candidate) == 0:
                feasible_components = self.components
            elif len(candidate) == len(self.weights) - 1:
                first = candidate[0]
                last = candidate[-1]
                feasible_components = [c for c in self.components if c.element[0] == last.element[1] and c.element[1] == first.element[0]]
            else:
                last = candidate[-1]
                already_visited = [c.element[0] for c in candidate]
                already_visited.extend([c.element[1] for c in candidate])
                already_visited = set(already_visited)
                feasible_components = [c for c in self.components if c.element[0] == last.element[1] and c.element[1] not in already_visited]
            if len(feasible_components) == 0:
                candidate = []
            else:
                # Choose a feasible component
                if random.random() <= self.bias:
                    next_component = max(feasible_components)
                else:
                    next_component = selectors.fitness_proportionate_selection(random, feasible_components, {'num_selected': 1})[0]
                candidate.append(next_component)
        return candidate
Return a candidate solution for an ant colony optimization.