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dwils098

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I concur, the theory is not necessary to understand how to use it. Perhaps it is counter-intuitive and one would like hone their intuition. Still there are much better approaches to developing an adequate intuition than the theory, this is why traditional Math textbooks rely on exposition first, to establish the context of the theory...

True. This is what I meant by confusing, without properly defining the variables at play, in this context, k is the index of the element of the ordered list, and not the kth smallest element.

Semantics, I agree, but confusing nonetheless.

Or in other words, how do we define k?

Context can be clarified by writing: "Quickselect is a selection algorithm to find the INDEX OF THE kth smallest element in an unordered list. It is closely related to the quicksort sorting algorithm."

Input: arr = [7, 4, 6, 3, 9, 1] k = 2

Output: k’th smallest element in the array is 4

Am I missing something... shouldn't the k'th smallest element in this array be 3, given that k=2?

Cost of the machine is amortized over the number of e-mail sent, in other words OP is more interested in the average cost of sending an e-mail message, using statistical approximation... (i.e.: sending an e-mail from USA to China on average requires x amount of servers, middle-servers, data-centers, and these process y amount of requests per minute, with a cost of operation of z on average per minute, etc.)

see: https://www.quora.com/How-much-does-it-cost-to-send-an-email...

DES : - (Matsui, M. (1994, January). Linear cryptanalysis method for DES cipher. In Advances in Cryptology—EUROCRYPT’93 (pp. 386-397). Springer Berlin Heidelberg.)

- Biham, E., & Shamir, A. (1991). Differential cryptanalysis of DES-like cryptosystems. Journal of CRYPTOLOGY, 4(1), 3-72.

AES : - Billet, O., Gilbert, H., & Ech-Chatbi, C. (2005, January). Cryptanalysis of a white box AES implementation. In Selected Areas in Cryptography (pp. 227-240). Springer Berlin Heidelberg.

- Bogdanov, A., Khovratovich, D., & Rechberger, C. (2011). Biclique cryptanalysis of the full AES. In Advances in Cryptology–ASIACRYPT 2011 (pp. 344-371). Springer Berlin Heidelberg.