Difference between revisions of "Talk:TADM2E 3.28"

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(Perform in single pass)
 
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I think this can be done in a single loop essentially taking two passes at once.  Here is a Python snippet.
 
I think this can be done in a single loop essentially taking two passes at once.  Here is a Python snippet.
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  <nowiki>
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  <source lang="Python">
 
# O( n) - len( input_values)
 
# O( n) - len( input_values)
 
length = len( input_values) # the length of the input values
 
length = len( input_values) # the length of the input values
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     backIndex -= 1
 
     backIndex -= 1
 
     answers[ backIndex] *= backProduct
 
     answers[ backIndex] *= backProduct
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  </nowiki>
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  </source>
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Note by murrayc:
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I think this should be the main solution, and I think this helps to visualise what is happening:
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 +
{| class="wikitable" |
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! a
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! b
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! c
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! d
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! e
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|-
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|colspan="5"| Forwards:
 +
|-
 +
|
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| '''a'''
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|
 +
|
 +
|
 +
|-
 +
|
 +
| a
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| '''ab'''
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|
 +
|
 +
|-
 +
|
 +
| a
 +
| ab
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| '''abc'''
 +
|
 +
|-
 +
|
 +
| a
 +
| ab
 +
| abc
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| '''abcd'''
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|-
 +
|colspan="5"| Backwards:
 +
|-
 +
|
 +
| a
 +
| ab
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| (abc) '''(e)'''
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| abcd
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|-
 +
|
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| a
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| (ab) '''(ed)'''
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| (abc) (e)
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| abcd
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|-
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|
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| (a) '''(edc)'''
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| (ab) (ed)
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| (abc) (e)
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| abcd
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|-
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| '''(edcb)'''
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| (a) (edc)
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| (ab) (ed)
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| (abc) (e)
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| abcd
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|-|}
 +
 
 +
--[[User:Murrayc2|Murrayc2]] ([[User talk:Murrayc2|talk]]) 07:29, 8 November 2015 (EST)

Latest revision as of 12:30, 8 November 2015

I think this can be done in a single loop essentially taking two passes at once. Here is a Python snippet. 

# O( n) - len( input_values)
length = len( input_values)		# the length of the input values
answers = [1]*length			# output values
frontIndex = 0				# the index at which we have calculated the product of all preceding indexes
frontProduct = 1			# the product of values preceding the front index
backProduct = 1				# the product of values following the back index
limit = length-1
backIndex = limit			# the index at which we have calculated the product of all following values
while( frontIndex < limit):
    frontProduct *= input_values[ frontIndex]
    backProduct *= input_values[ backIndex]
    frontIndex += 1
    answers[ frontIndex] *= frontProduct
    backIndex -= 1
    answers[ backIndex] *= backProduct


Note by murrayc:

I think this should be the main solution, and I think this helps to visualise what is happening:

--Murrayc2 (talk) 07:29, 8 November 2015 (EST)
a b c d e
Forwards:
a
a ab
a ab abc
a ab abc abcd
Backwards:
a ab (abc) (e) abcd
a (ab) (ed) (abc) (e) abcd
(a) (edc) (ab) (ed) (abc) (e) abcd
(edcb) (a) (edc) (ab) (ed) (abc) (e) abcd
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