Btukfyl

This question is derived from this other question, where @marmot solved it nicely. However, that solution assumes the cycle will always have a number of nodes more or less like 11. When you apply that solution to a cycle with, say, 4 nodes, the cycle looks more like a square.

How could we change those arrows to present themselves more like a circle? Ideally it would look like an ellipse with radii as near as possible to the $rho$ letter, but a circle would do just fine.

documentclass[tikz,border=3.14mm]{standalone}

usetikzlibrary{chains,positioning}

begin{document}



begin{tikzpicture}[node distance=1cm]

node[circle,minimum width=7cm] (circ) {};

foreach X [count=Y] in {32,25,50,17}

{node  (cnY) at ({-(Y-2.5)*360/4}:3.5) {$X$}; }

foreach Y [remember=Y as LastY (initially 4)]in {1,...,4}

{draw[-latex,shorten >=4pt,shorten <=4pt] (cnLastY) to[bend left=10] (cnY);}



begin{scope}[start chain = going below,

  every node/.append style={on chain,,xshift=-{cot(76)*1.5cm}},

  every join/.style=latex-]

node[below=of cn4] (n0) {$36$};

draw[latex-] (cn4) -- (n0);

node[join] (n6) {$9$};

node[join] (n5) {$1$};

node[join] (n4) {$24$};

node[join] (n3) {$4$};

node[join] (n2) {$46$};

node[join] (n1) {$12$};

node[join] (n0) {$2$};

end{scope}



end{tikzpicture}

end{document}

Sorry for the confusion. I did not think about arbitrary numbers of nodes, but I should. Here is a version that draws the connections on a precise circle. (In Zarko's nice answer there are still parameters that need to be adjusted by hand. Yet it is true that for long arcs arcs tend to look better than bend left.) The disadvantage is that it takes a while to compile.

documentclass[tikz,border=3.14mm]{standalone}

usetikzlibrary{chains,positioning,calc,intersections}

begin{document}



begin{tikzpicture}[node distance=1cm]

pgfmathsetmacro{Radius}{3.5}

path[name path=big circle] (0,0) circle (Radius cm);

foreach X [count=Y] in {32,25,50,17}

{node[name path global=Y-circ,inner sep=4pt,circle]  (cnY) at 

({-(Y-2.5)*360/4}:Radius) {$X$}; }

foreach Y [remember=Y as LastY (initially 4)]in {1,...,4}

{

path[name intersections={of=big circle and LastY-circ,by={aux0,aux2},sort

by=big circle},

name intersections={of=big circle and Y-circ,by={aux1,aux3},sort

by=big circle}];

draw[-latex] 

let p1=($(aux0)-(0,0)$),p2=($(aux3)-(0,0)$),

n1={atan2(y1,x1)},n2={atan2(y2,x2)},

n3={(ifthenelse(n2<n1,n2,n2-360)} in 

(aux0) arc(n1:n3:Radius);

}



begin{scope}[start chain = going below,

  every node/.append style={on chain,,xshift=-{cot(76)*1.5cm}},

  every join/.style=latex-]

node[below=of cn4] (n0) {$36$};

draw[latex-] (cn4) -- (n0);

node[join] (n6) {$9$};

node[join] (n5) {$1$};

node[join] (n4) {$24$};

node[join] (n3) {$4$};

node[join] (n2) {$46$};

node[join] (n1) {$12$};

node[join] (n0) {$2$};

end{scope}

end{tikzpicture}

end{document}

Alternatively one can find approximate values to be fed into bend left. The following code compiles much faster but not yield exact circles.

documentclass[tikz,border=3.14mm]{standalone}

usetikzlibrary{chains,positioning,calc}

begin{document}



begin{tikzpicture}[node distance=1cm]

pgfmathsetmacro{Radius}{3.5}

foreach X [count=Y] in {32,25,50,17}

{node[inner sep=4pt,circle]  (cnY) at 

({-(Y-2.5)*360/4}:Radius) {$X$}; }

foreach Y [remember=Y as LastY (initially 4)]in {1,...,4}

{

path (cnLastY) -- (cnY) coordinate[pos=0](aux0) coordinate[pos=1](aux1);

draw[-latex] 

let p1=($(aux0)-(0,0)$),p2=($(aux1)-(0,0)$),

n1={atan2(y1,x1)},n2={atan2(y2,x2)},

n3={0.45*(n1-ifthenelse(n2<n1,n2,n2-360)} in 

(cnLastY) to[bend left=n3] (cnY);

}



begin{scope}[start chain = going below,

  every node/.append style={on chain,,xshift=-{cot(76)*1.5cm}},

  every join/.style=latex-]

node[below=of cn4] (n0) {$36$};

draw[latex-] (cn4) -- (n0);

node[join] (n6) {$9$};

node[join] (n5) {$1$};

node[join] (n4) {$24$};

node[join] (n3) {$4$};

node[join] (n2) {$46$};

node[join] (n1) {$12$};

node[join] (n0) {$2$};

end{scope}

end{tikzpicture}

end{document}