我如何构建树形图？

Question

我想要如图所示的

Answer 1

最小努力问题 ⇒ 最小努力答案

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{graphs,graphdrawing}
\usegdlibrary{trees}
\begin{document}

\begin{tikzpicture}
  \graph[tree layout,grow=right,fresh nodes] {
    "" -- {
      "1" -- {
        "3 (1,3)",
        "5 (1,5)" 
      },
      "2" -- {
        "3 (2,3)",
        "5 (2,5)" 
      },
      "4" -- {
        "3 (4,3)",
        "5 (4,5)"
      }
    }
  };
\end{tikzpicture}

\end{document}