# What are the "must known" algorithms for online programming contests?

**URL:** <https://discuss.codechef.com/t/what-are-the-must-known-algorithms-for-online-programming-contests/2717>\
**Category:** tutorial\
**Tags:** algorithm\
**Created:** [July 24, 2013, 1:02pm UTC](https://discuss.codechef.com/t/what-are-the-must-known-algorithms-for-online-programming-contests/2717 "2013-07-24T13:02:10Z")\
**Posts on this page:** 1\
**Showing post:** 8

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**Author:** ![code\_master01](https://www.codechef.com/sites/all/themes/abessive/images/user_default_thumb.jpg) [@code\_master01](https://discuss.codechef.com/u/code_master01)\
**Post date:** [August 14, 2013, 10:16am UTC](https://discuss.codechef.com/t/what-are-the-must-known-algorithms-for-online-programming-contests/2717/8 "2013-08-14T10:16:40Z")

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I’d suggest further adding

- Heavy Light decomposition in trees
- [Inverse Modulo operations](http://comeoncodeon.wordpress.com/2011/10/09/modular-multiplicative-inverse/)
- [Lucas theorem method for nCr](http://discuss.codechef.com/questions/3869/best-known-algos-for-calculating-ncr-m)
- [Pollard Rho Integer Factorization](http://comeoncodeon.wordpress.com/2010/09/18/pollard-rho-brent-integer-factorization/)
- [Catalan Numbers](http://en.wikipedia.org/wiki/Catalan_number)

Some useful resources : [come on code on](http://comeoncodeon.wordpress.com/)

Some cool problems : [Nikhil Garg’s blog on quora](http://www.quora.com/Nikhil-Garg/Algorithmic-Programming-Problems)

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