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题目:有一分数序列:2/1,3/2,5/3,8/5,13/8,21/13…求出这个数列的前20项之和。
方法一:
#!/usr/bin/python
# -*- coding: UTF-8 -*-
a = 2.0
b = 1.0
s = 0
for n in range(1,21):
s += a / b
t = a
a = a + b
b = t
print s
方法二:
#!/usr/bin/python
# -*- coding: UTF-8 -*-
a = 2.0
b = 1.0
s = 0.0
for n in range(1,21):
s += a / b
b,a = a , a + b
print s
s = 0.0
for n in range(1,21):
s += a / b
b,a = a , a + b
print s
方法三:
#!/usr/bin/python
# -*- coding: UTF-8 -*-
a = 2.0
b = 1.0
l = []
l.append(a / b)
for n in range(1,20):
b,a = a,a + b
l.append(a / b)
print reduce(lambda x,y: x + y,l)