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Topic: kth largest element from the 2-d array (Read 5399 times) |
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spur
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kth largest element from the 2-d array
« on: Feb 10th, 2013, 1:18pm » |
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Given a 2 D array. The rows and columns are sorted.
Find the kth largest element from the 2-d array.
e,g input array:
1 2 3 25
4 23 20 88
7 82 90 100
8 83 91 101
k=5
output:88
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birbal
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Re: kth largest element from the 2-d array
« Reply #1 on: Mar 14th, 2013, 9:13am » |
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Remove the largest element from the matrix and create a hole. Now from all the neighbouring elements, find the largest and move it to hole thereby creating another hole. Keep on moving this hole up and left till the smallest element is moved. Repeat this k times.
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Grimbal
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Re: kth largest element from the 2-d array
« Reply #2 on: Mar 15th, 2013, 9:59am » |
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You don't need to continue moving the hole after you moved x steps left and y steps up and xy>k (x+1)(y+1)>k .
Where k is the number of elements you still need to extract.
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| « Last Edit: Apr 7th, 2013, 7:42am by Grimbal » |
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Spicyy
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Re: kth largest element from the 2-d array
« Reply #3 on: Apr 5th, 2013, 11:32am » |
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I think we has to go till K steps , May be i am wrong 
@Grimbal suppose in a given example we has to find 15th largest element, then according to you we will stop once we fetch 8 and 25 since that time left = 4 and up = 4 so 4*4 > 15 but 2 is still inside the matrix
plz correct me if i am wrong 
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Grimbal
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Re: kth largest element from the 2-d array
« Reply #4 on: Apr 7th, 2013, 7:41am » |
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I have to correct my statement,
it is not xy>k but (x+1)(y+1)>k
But you don't fetch 8 and 25 at the same time.
When in the process of moving the hole you moved the 8 right (and the hole is where the 8 was), then you have x=3 and y=0 and (x+1)(y+1) = 4.
By the way, the original example is incorrect, since 20 is found right of a 23
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| « Last Edit: Apr 7th, 2013, 7:45am by Grimbal » |
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