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Topic: Merge Arrays in constant space and linear time (Read 1998 times) |
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hary
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Merge Arrays in constant space and linear time
« on: Feb 6th, 2010, 1:10am » |
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Merge two sorted arrays one containing "m" elements and other caontaining "n" elements. We need to do this in constant space. Most of us know that linear time complexity for merging is possible. I am wondering if tconstant space complexity is possible. Can someone comment.
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birbal
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Re: Merge Arrays in constant space and linear time
« Reply #1 on: Feb 6th, 2010, 1:20am » |
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on Feb 6th, 2010, 1:10am, hary wrote:Merge two sorted arrays one containing "m" elements and other caontaining "n" elements. We need to do this in constant space. Most of us know that linear time complexity for merging is possible. I am wondering if tconstant space complexity is possible. Can someone comment.
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I dont think constant space complexity is possible. But yes you can do it with min( m, n) extra space.
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newb
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Re: Merge Arrays in constant space and linear time
« Reply #2 on: Feb 6th, 2010, 2:55am » |
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Quote:Merge two sorted arrays one containing "m" elements and other caontaining "n" elements. We need to do this in constant space. Most of us know that linear time complexity for merging is possible. I am wondering if tconstant space complexity is possible. Can someone comment.
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where to store the merged arrays?
we must have space for that.
or do we have a single array of m+n size in which first m elemnts are sorted and last n elements are sorted?
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towr
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Re: Merge Arrays in constant space and linear time
« Reply #3 on: Feb 6th, 2010, 3:23am » |
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See here and here.
In summary, it's possible, but it's so complicated no one here has tried to post an algorithm for it 
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bmudiam
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Re: Merge Arrays in constant space and linear time
« Reply #4 on: Feb 8th, 2010, 7:17pm » |
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You can do merging in O(N), if the elements are maintained in a singly linked list.
Actually, you can do merge sort also using singly linked list in O(nlogn) without using any extra space.
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| « Last Edit: Feb 8th, 2010, 7:18pm by bmudiam » |
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towr
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Re: Merge Arrays in constant space and linear time
« Reply #5 on: Feb 9th, 2010, 3:26am » |
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on Feb 8th, 2010, 7:17pm, bmudiam wrote:| You can do merging in O(N), if the elements are maintained in a singly linked list. |
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Yes, but we don't have a linked list, we have an array. That's what makes the problem problematic.
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