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Editorial Team
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Asked: 2026-05-20T04:59:39+00:00

this is a google interview question : Given a N*N Matrix. All rows are

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this is a google interview question :

Given a N*N Matrix.
All rows are sorted, and all columns are sorted.
Find the Kth Largest element of the matrix.

doing it in n^2 is simple and we can sort it using heap or merge sort (n lg n) and then get it, but is there a better approach, better than (n lg n)?

example of the array ::

 1   5   7  12
 3   6   8  14
 4   9  10  15
11  17  19  20

1<5<7<12 and 1<3<4<11 similarly the other rows and columns. now say we need to find the 10th smallest element, in here it is 11..hope this adds some detail to the question…

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1 Answer

  1. Editorial Team

    Yes, there is an O(K) algorithm due to Frederickson and Johnson.

    Greg N. Frederickson and Donald B. Johnson. Generalized Selection and Ranking: Sorted Matrices. SIAM J. Comput. 13, pp. 14-30. http://epubs.siam.org/sicomp/resource/1/smjcat/v13/i1/p14_s1?isAuthorized=no

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