[EMAIL PROTECTED] wrote:
I'm trying to come up with a good algorithm to do the following:
Given a list 'A' to be operated on, and a list 'I' of indices into 'A',
rotate the i'th elements of 'A' left or right by one position.
Here's are some examples:
A = [a, b, c, d, e, f]
I = [0, 3, 4]
rotate(A, I, 'left') --> [b, c, d, e, f, a]
rotate(A, I, 'right') --> [b, a, c, f, d, e]
I = [1, 3, 4]
rotate(A, I, 'left') --> [b, a, d, e, c, f]
rotate(A, I, 'right') --> [a, c, b, f, d, e]
Any ideas?
class CBuf:
def __init__(self,list=[]):
self.List = list
self.Front = 0
def ActualIndexGet(self,index):
return (self.Front + index) % len(self.List)
def ValueGet(self,index):
return self.List[self.ActualIndexGet(index)]
def Rotate(self,dir):
if dir == 'L':
self.Front += 1
else:
self.Front -= 1
self.Front = self.Front % len(self.List)
def Show(self):
i = self.Front
while 1:
print self.List[i]," ",
i = (i+1) % len(self.List)
if i == self.Front:
break
print
b = CBuf(['a','b','c','d','e','f'])
b.Show()
b.Rotate('L')
b.Show()
b.Rotate('L')
b.Show()
>>> ================================ RESTART
================================
>>>
a b c d e f
b c d e f a
c d e f a b
>>>
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