什么是算法?

朗文词典里algorithm的定义是：a set of instructions that are followed in a fixed order and used for solving a mathematical problem, making a computer program etc.

辗转相除求两个数的最大公约数是个极端的例子，它用不到啥数据结构。

红黑树和B树则没啥高档数学计算，尤其是和求sin(x)等相比。Wirth说算法+数据结构＝程序。绝大多数程序是二者的交织，比如把π算到一亿位，除了公式，还有存放问题。

algorithm的来历是：

Date: 1600-1700;

Origin: algorism 'algorithm' (13-19 centuries),

from Medieval Latin algorismus,

from Arabic al-khuwarizmi,

from al-Khuwarizmi 9th-century Arab mathematician;

influenced by Greek arithmos 'number'