Tag Archives: HashSet

FoxAndClassroom: TopCoder Problem 12811

[The problem appeared in TopCoder SRM 594 (Div-2, Level-1)]
Problem link: http://community.topcoder.com/stat?c=problem_statement&pm=12811

Problem Statement:
Fox Ciel is now in high school. The seats in her classroom are arranged into an n by m matrix. The rows are numbered from 0 to n-1 (front to back) and the columns from 0 to m-1 (left to right).
At the beginning, Ciel can choose any of the seats. Then, at the end of each week Ciel will shift one row to the back and one column to the right, wrapping around whenever necessary. Formally, if her current seat is in row r and column c, then her seat next week will be the one in row ((r+1) modulo n) and column ((c+1) modulo m).
Fox Ciel now wonders whether she can sit in all the seats in the classroom if she follows the above procedure. As we already mentioned, she can start in any of the seats. Also, she can attend the school for as many weeks as she wants to. Return “Possible” if she can sit in all the seats and “Impossible” otherwise.
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Detect HTML Tags: Hackerrank

Problem link: https://www.hackerrank.com/challenges/detect-html-tags

Problem Statement:
In this problem you will use regular expressions to help you detect the various Tags used in an HTML document.

Here are a few examples of tags:

The “p” tag for paragraphs:

<p>This is a paragraph</p>

It is also okay to have one or more spaces before or after the tag name:

<  p >This is also a paragraph</p>

Then, there is also something called a void or an empty tag such as:


Some tags can also have attributes. For example, here we see the “a” tag which is used for adding links to a document.

<a href="http://www.google.com">Google</a> 

There are also tags such as this which haven’t been split into an opening and closing tag:

In the above case, “a” is the tag and “href” is an attribute, the value of which is “http://www.google.com”. Ignore any attributes. Your task is to find out all the tags present in the given document.
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Unfriendly Numbers: Hackerrank

Problem link: https://www.hackerrank.com/challenges/unfriendly-numbers

Problem Statement:
There is one friendly number and N unfriendly numbers. We want to find how many numbers are there which exactly divide the friendly number, but does not divide any of the unfriendly numbers.
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