递归小程序案例代码

# -*- coding:utf-8 -*-
 
__author__ = 'Abel Xu'
 
 
def func(n):
    """
    T(n) = 4T(n/2)+n
    = 2n^2-n
    :param n:
    :return:
    """
    if n==0:
        return 0
 
    return 4 * func(n/2) + n
 
# 另一套写法
f = lambda x: x and 4*f(x/2)+x or 0
 
if __name__ == '__main__':
 
    for i in xrange(0, 6, 2):
        print(func(i))
 
    print f(4)