private void calcHeuristic(TrieNode node) {
		if (node.isLeaf()) {
			node.setHeuristic(PRECISION_MULTIPLIER / node.getDepth());
		} else { 
			for (TrieNode child : node.getChildren().values()) {
				calcHeuristic(child);
			}
			node.setHeuristic(getMinChildHeuristic(node));
		}
	}