Htydjtk

I'd like to clean up my tree by drawing an edge between parent nodes. In the following, I'd like to have the 0 nodes (which are children now) adjacent to the numbered nodes (ie on the "parent" level). How might I do this? Am I missing something simple? Thanks!

documentclass{article}

usepackage{forest}

begin{document}



begin{forest}

for tree={circle, draw, l sep=20pt, s sep=5 mm}

[0, green

    [0, green]

    [1, red

        [0, green]

        [2, red

            [0, green]

            [3, red]

        ]

        [3, red

            [0, green]

            [2, red]

        ]

    ]

    [2, red

        [0, green]

        [1, red

            [0, green]

            [3, red]

        ]

        [3, red

            [0, green]

            [1, red]

        ]

    ]

    [3, red

        [0, green]

        [1, red

            [0, green]

            [2, red]        

        ]

        [2, red

            [0, green]

            [1, red]            

        ]

    ]

]

end{forest}

end{document}

by letting each 0 node be on the same level as the parents and connecting the parent.

That is, I'd like it to look something like

0 ----- 0

       / 

0 --- 1   2 --- 0

     / 

    2   3

This not really an answer but more to clarify if you want something of this sort.

documentclass{article}

usepackage{forest}

begin{document}

begin{forest}

for tree={circle, draw, l sep=20pt, s sep=15mm}

[0, green,alias=L1

%    [0, green]

    [1, red,alias=L2

%        [0, green]

        [2, red,alias=L3

%            [0, green]

            [3, red]

        ]

        [3, red,alias=L4

%            [0, green]

            [2, red]

        ]

    ]

    [2, red,alias=L5

%        [0, green]

        [1, red,alias=L6

%            [0, green]

            [3, red]

        ]

        [3, red,alias=L7

%            [0, green]

            [1, red]

        ]

    ]

    [3, red,alias=L8

%        [0, green]

        [1, red,alias=L9

%            [0, green]

            [2, red]        

        ]

        [2, red,alias=L10

%            [0, green]

            [1, red]            

        ]

    ]

]

foreach X in {1,...,10}

{ifnumX=1

draw (LX) -- ++ (-1.5cm,0) node[circle,left,draw,green]{0};

else

draw (LX) -- ++ (-1cm,0) node[circle,left,draw,green]{0};

fi}

end{forest}

end{document}

Not a tikz-tree solution: I just try to replicate your graph using normal TikZ

documentclass[tikz,margin=3mm]{standalone}

usetikzlibrary{calc}

begin{document}

begin{tikzpicture}

node [circle,draw] (0c) at (0,0) {0};

node [circle,draw] (1) at ($(0c)+(-120:1.5)$) {1};

node [circle,draw] (2r) at ($(0c)+(-60:1.5)$) {2};

node [circle,draw] (2l) at ($(1)+(-120:1.5)$) {2};

node [circle,draw] (3) at ($(1)+(-60:1.5)$) {3};

node [circle,draw] (0al) at ($(0c)+(-1.5,0)$) {0};

node [circle,draw] (0bl) at ($(1)+(-1.5,0)$) {0};

node [circle,draw] (0r) at ($(2r)+(1.5,0)$) {0};

draw (0c)--(1)

    (0c)--(2r)

    (1)--(2l)

    (1)--(3)

    (0c)--(0al)

    (1)--(0bl)

    (2r)--(0r);

end{tikzpicture}

end{document}