弯曲的箭头 Tikz

Question

我想在 Latex 中重新创建以下图像以完成我的作业。但是，我无法弯曲箭头，如下图所示。请帮助我实现这一点。提前致谢！

编辑

\documentclass[12pt]{article}
\usepackage{tikz}
\begin{document}

\begin{center}
\begin{tikzpicture}[scale=0.2]
\tikzstyle{every node}+=[inner sep=0pt]
\draw [black] (3.3,-3.2) circle (3);
\draw (3.3,-3.2) node {$Q_0$};
\draw [black] (29.2,-3.2) circle (3);
\draw (29.2,-3.2) node {$Q_1$};
\draw [black] (6.3,-3.2) -- (26.2,-3.2);
\fill [black] (26.2,-3.2) -- (25.4,-2.7) -- (25.4,-3.7);
\draw (16.25,-3.7) node [below] {$u$};
\end{tikzpicture}
\end{center}

\end{document}

这是一个简单的过渡，我想改变这个过渡。

Answer 1

给你！

PS：[pos=.1]让我有点困惑^^

\documentclass[tikz,border=5mm]{standalone}
\begin{document}
\begin{tikzpicture}[>=stealth,teal,font=\sffamily]
\path[nodes={circle,minimum size=8mm,fill=cyan!30,draw=teal}]
(0,0)   node (P) {P}        
(3,.5)  node (Q) {Q}
(6,-1)  node (R) {R}
;
\draw (R.center) circle(.35);
\draw[<-] (P.180)--+(180:1);
\draw[->] (P) .. controls +(-10:4) and +(170:1.5) .. (Q) node[pos=.1,above]{u}; 
\draw[->] (Q.30) .. controls +(20:1) and +(60:.5) .. (Q.90) node[pos=.5,right]{v};
\draw[->] (Q.-45) .. controls +(-45:4) and +(190:1) .. (R.180) node[pos=.1,below left]{w};
\end{tikzpicture}
\end{document}