尾递归

函数递归调用自身的技巧叫做递归

递归是很神奇的概念。所有学编程和有志于解答世上最复杂的难题的人，都一定要好好理解一下什么是递归。

而尾递归是一种我们通常称之为“迭代”的递归方式。这篇文章无法确切地教给你到底什么是递归什么是尾递归，因为它们的真正含义需要有志者仔细体会。

尾递归

尾递归是带着一个“迭代变量”不断向深处递归，相当于边递归，边计算，等递归完成时，结果也计算出来了。

In computer science, a tail call is a subroutine call performed as the final action of a procedure. If the target of a tail is the same subroutine, the subroutine is said to be tail-recursive, which is a special case of direct recursion. Tail recursion (or tail-end recursion) is particularly useful, and often easy to handle in implementations.
尾递归是返回递归关系最后一个动作的递归方式。

而递归中不计算任何值，到最后Return时递归求解。

递归和迭代（尾递归）的Fibonacci Numbers实现

## The Recursion and Iteration implemention by qianxin
## Dedicated to Fibonacci(1170—1250)

## Recursion Fibonacci Numbers
def Rfib(i):
    if(i == 1 or i == 2):
        return 1
    else:
        return Rfib(i-1)+Rfib(i-2)

## Iteration Fibonacci Numbers
def Ifib(i, a, b):
    if(i == 1 or i == 2):
    # That's a Iteration! By Tail Recursion
        return b
    else:
        return Ifib(i-1, b, a+b)

献给Fibonacci(1170—1250)。