please can someone point out error in my logic of solving delivery man problem from codechef.::
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Binary Indexed Trees (aka Fenwick Tree)
The motivation for binary indexed trees is similar to that of segment trees. However, note that segment trees are much more flexible than binary indexed trees, and usually its true that any problem that can be solved with BIT can be solved with segment trees but not the other way around.
Video tutorial: This is a superb tutorial, giving the motivation, walking through example, and going step-by-step through the pseudocode.
It depends on what kind of website. Acutally Aman, this is not the place where you can get your desired response. This is actually for Competitive Programming. I recommend posting this question in the web forum, I think you will get better responses.
A Detailed Description of DES and 3DES Algorithms (Data Encryption Standard and Triple DES)
While many ciphers have been created based upon the Feistel structure, the most famous of these is the Data Encryption Standard (DES). DES was based off of the original Lucifer cipher developed by Feistel and Coppersmith and submitted as an entry to the US National Bureau of Standards as a candidate for the US official encryption standard. After some modification (to improve security against differential cryptanalysis), it was selected and published as a standard in 1977.
Encryption with DES
The DES algorithm is a 16-round Feistel cipher. It takes as input a 64-bit input and a 64-bit secret key, and consists of three main stages:
The initial permutation
The round function (repeated 16 times)
The final permutation
A diagram of how these stages fit together with the ...