Traverse every unique path (from root to leaf) in an arbitrary tree structure

Question

I have several lists:

A = [\"a0\", \"a1\"]       // the number of lists varies
B = [\"b0\", \"b1\", \"b2\"] // such as the number of elements in a list.
C = [\"c         


        

Answer 1

Something that I came up with working on printing the words in a TrieTree that can be easily adaptable to other kinds of trees or different needs:

public void rootToLeaves() {
    HashMap hashMap = new HashMap();
    for(TrieNode trieNode : root.getChildren())
        rootToLeaves(trieNode, hashMap, 0);
}

private void rootToLeaves( TrieNode trieNode, HashMap hashMap, int heightIndex ) {
    hashMap.put(heightIndex, trieNode);

    if( trieNode.isLeaf() )
        printValues(hashMap, heightIndex);
    else
        for( TrieNode childNode : trieNode.getChildren() )
            rootToLeaves( childNode, hashMap, heightIndex + 1 );
}

private void printValues(HashMap hashMap, int heightIndex) {
    for(int index = 0; index <= heightIndex; index++)
        System.out.print(hashMap.get(index).getValue());
    System.out.println();
}

This solution does a nice job in terms of memory management (It uses a single HashMap whose size will never exceed the height of the tree) and it offers a lot of flexibility (Just replace printValues with whatever you need).

NOTE: Knowing the height of the tree in advance will let you use a simple Array instead of a Map.