# 来自jb51.cc 
一些初级python面试题，这里简单罗列一下
# 反转字符串， 这个是最常见的
# 比如给一个字符串hello,将其反转为olleh
def reverse(str):
    alist = list(str)
    alist.reverse()
    new_str = ''.join(alist)
    return new_str


    
    
# 写一个方法打印如下内容,每一行打印5个
# server1,server2,server3,server4,server5(换行)
# server6,server7,server8,server9,server10(换行)
# server11,server12,server13,server14,server15(换行)
# server16,server17,server18,server19,server20(换行)
# ...
# server996,server997,server998,server999,server1000
 
#正确写法1
for i in range(1,1000):
    if (i % 5 == 1):
        a = i + 1
        b = i + 2
        c = i + 3
        d = i + 4
        print('server' + str(i) + ',' + 'server' + str(a) + ',' + 'server' + str(b) + ',' + 'server' + str(c) + ',' 'server' + str(d))
 
#正确写法2
for i in range(1,1004):
    if (i % 5 == 0):
        a = i - 4
        b = i - 3
        c = i - 2
        d = i - 1
        print('server' + str(a) + ',' + 'server' + str(d) + ',' 'server' + str(i))
 
#注意难点
#print语句每运行一次，都是另起一行，因此完全不必要写一个\n
 
#以下是错误写法
for i in range(1,1000):
    if (i % 5 == 0):
       print('server' + str(i) + '\n')
    else:
        print('server' + str(a) + ',')
#这种写法的运行结果是
server1, 
server2, 
server3, 
server4, 
server5
 
server6, 
server7, 
server8, 
server9, 
server10
 
server11, 
server12, 
server13, 
server14, 
server15
 
server16,......



# 给一个dir,循环遍历该dir下面的所有文件(只列出文件,不要文件夹).
import os
def get_file_names(dir):
 
    alist = os.listdir(dir)
    path = os.path.realpath(dir)
    result = []
    for i in alist:
        ipath = os.path.join(path,i)
        if os.isdir(ipath):
            #get_file_name(ipath)
            result.extend(get_file_name(ipath))
        else:
            result.append(ipath)
    return result 

    
    
    
# Given an array of integers,return indices of the two numbers
# such that they add up to a specific target.
# You may assume that each input would have exactly one solution.
# 给了一个全是数字的列表,现在让列表中任意2个数字相加,得到一个指定target,# 然后返回这2个数字的index
# Example:
# Given nums = [2,7,11,15],target = 9,#
# Because nums[0] + nums[1] = 2 + 7 = 9,# return [0,1].
def two_sum(nums,target):
 
    for a in (0,len(nums)):
        b = a + 1
        res1 = 0
        res2 = 0
 
        for i in (b,len(nums)):
            if ( nums[a] + nums[i] == target ):
                res1 = a
                res2 = i
    return [res1,res2]