python作业

[root@web sbin]# cat task1.py 
#!/usr/bin/env python

sum = 0
for i in xrange(1, 101):
    sum += i
print sum

[root@web sbin]# python task1.py 
5050

[root@web sbin]# cat task2.py 
#!/usr/bin/env python

sum = 0
for i in xrange(1, 501):
    if i % 2 != 0:
        sum += i
print sum

[root@web sbin]# python task2.py 
62500

[root@web sbin]# cat task3.py   
#!/usr/bin/env python

def fact(n):
    sum = 1
    for i in xrange(1, n+1):
        sum *= i
    return sum

if __name__ == ‘__main__‘:
    a = 0
    for i in xrange(1, 21):
        a += fact(i)
    print a

[root@web sbin]# python task3.py
2561327494111820313

In [1]: l = [2,32,43,453,54,6,576,5,7,6,8,78,7,89]

In [2]: l.sort()         //正序排序

In [3]: l
Out[3]: [2, 5, 6, 6, 7, 7, 8, 32, 43, 54, 78, 89, 453, 576] 

In [4]: l.reverse()          //反序排序

In [5]: l
Out[5]: [576, 453, 89, 78, 54, 43, 32, 8, 7, 7, 6, 6, 5, 2]