print all root to leaf paths in a binary tree

Question

i am trying to print all root to leaf paths in a binary tree using java.

public void printAllRootToLeafPaths(Node node,ArrayList path) 
{
    if(node==null)         


        

Answer 1

Here is the correct Implementation

public static > List> printAllPaths(BinaryTreeNode node) {
    List > paths = new ArrayList>();
    doPrintAllPaths(node, paths, new ArrayList());
    return paths;
}

private static > void doPrintAllPaths(BinaryTreeNode node, List> allPaths, List path) {
    if (node == null) {
        return ;
    }
    path.add(node.getData());
    if (node.isLeafNode()) {
        allPaths.add(new ArrayList(path));   

    } else {
        doPrintAllPaths(node.getLeft(), allPaths, path);
        doPrintAllPaths(node.getRight(), allPaths, path);
    }
    path.remove(node.getData());
}

Here is the test case

@Test
public void printAllPaths() {
    BinaryTreeNode bt = BinaryTreeUtil.fromInAndPostOrder(new Integer[]{4,2,5,6,1,7,3}, new Integer[]{4,6,5,2,7,3,1});
    List > paths = BinaryTreeUtil.printAllPaths(bt);

    assertThat(paths.get(0).toArray(new Integer[0]), equalTo(new Integer[]{1, 2, 4}));
    assertThat(paths.get(1).toArray(new Integer[0]), equalTo(new Integer[]{1, 2, 5, 6}));
    assertThat(paths.get(2).toArray(new Integer[0]), equalTo(new Integer[]{1, 3, 7}));

    for (List list : paths) {          
        for (Integer integer : list) {
            System.out.print(String.format(" %d", integer));
        }
        System.out.println();
    }
}

Here is the output

1 2 4

1 2 5 6

1 3 7