Chapter 5 DOT
大型問題如何拆解成小問題並形成清楚的問題解決程式流程，DOT是圖像化演算流程思維的標準架構
Graph description language
Reference:
* https://www.graphviz.org/pdf/dotguide.pdf
* 10 個改變世界的演算法
5.1 What is Graph?
In mathematics, and more specifically in graph theory, a graph is a structure amounting to a set of objects in which some pairs of the objects are in some sense “related”. The objects correspond to mathematical abstractions called vertices (also called nodes or points) and each of the related pairs of vertices is called an edge (also called link or line). Typically, a graph is depicted in diagrammatic form as a set of dots or circles for the vertices, joined by lines or curves for the edges. Graphs are one of the objects of study in discrete mathematics.