Discussion on the application of the recursion law in the programming

Recursion is not only an important method which should be mastered by the middle school students in information science competitions,but also necessary in teaching programming.The recursion arithmetic is to use some steps of simple repeated calculation to describe the complex problems.Two relations must be found out in solving recursion problems: the original condition and the recursion formula,and the second one is the key.man usually uses loops to implement recursion arithmetic.