Category Archives: Algorithms & Data structures

Algorithms and data structures.

C++: Unordered maps and sets for non-primitive types

Since C++ 11, we can use unordered sets and unordered maps. However, these data structures only seem to work with primitive types and strings. If you need a pair or a vector as the key, you’re out of luck. Fortunately, … Continue reading

Posted in Algorithms & Data structures, Posts, ShortPosts, SoftwareEngineering | Leave a comment

QuickSelect

Theory Quickselect on Wikipedia Implementation in C++ Practice https://leetcode.com/problems/kth-largest-element-in-an-array/

Posted in Algorithms & Data structures, Posts, SoftwareEngineering | Leave a comment

Fenwick tree (aka Binary Indexed Tree)

Theory TopCoder – Binary Indexed Trees Algorithms Live – Fenwick tree Wikipedia – Fenwick tree Implementation in C++ Practice Kattis – Movie collection AtCoder – B Fenwick Tree

Posted in Algorithms & Data structures, Posts, SoftwareEngineering | Leave a comment

Disjoint Set Union (aka Union-Find)

Theory Algorithms, 4th edition by Robert Sedgewick, Kevin Wayne 1.5   Case Study: Union-Find Union Find on Cubits.ai Implementation in C++ Practice https://atcoder.jp/contests/practice2/tasks/practice2_a

Posted in Algorithms & Data structures, Posts, SoftwareEngineering | Leave a comment

Isolate the rightmost (least-significant) bit

Fast & elegant: Tests Output Brute force Output for the new version Practice 231. Power of Two 191. Number of 1 Bits Related concepts Two’s complement

Posted in Algorithms & Data structures, Posts, ShortPosts | Leave a comment

Kadane’s algorithm

I just learned about this algorithm, which is considered a dynamic programming approach. However, depending on the implementation, it might not resemble dynamic programming at all. Check out the implementation presented on Wikipedia: That does not look like dynamic programming … Continue reading

Posted in Algorithms & Data structures, Posts | Leave a comment

Interesting programming problems

The following problems were either difficult to solve, provided a valuable learning, or both. I’m putting them here so as not to forget a bout them. Drinks Three Pairwise Maximums FashionabLee Captain Flint and Crew Recruitment

Posted in Algorithms & Data structures, Posts | Leave a comment

Algorithms live, Episode 0 – Notes

One of my goals this year is to catch up with Algorithms Live and as part of that, I’ll be posting my notes for each episode and possibly the solutions to the proposed problems. Episode https://www.youtube.com/watch?v=kPaJfAUwViYSorry, as of now I … Continue reading

Posted in Algorithms & Data structures, Posts | Leave a comment

My C++ template for programming puzzles

Posted in Algorithms & Data structures, Home | Leave a comment