语法基础题

1. 列表排序：

L=[5,4,3,2,1]
L.sort()
print L
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L=[5,4,3,2,1]
for i in range(len(L)):
    index=i
    for j in range(i+1,len(L)):
      if (L[index]>L[j]):
        index=j
    L[index],L[i]=L[i],L[index]
print L

2. 字符串逆序

L="abcdefg"
print (L[::-1])
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#先将字符串转换为列表，再列表反转，最后再将列表组成字符串
L="abcdefg"
L=list(L)
L.reverse()
print(''.join())
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L="abcdefg"
L1=list(L)
for i in range(len(L)):
  L1[i]=L[-1-i]
print ''.join(L1)