CoolMind

If you cannot measure it, you cannot improve it.

Pick a number randomly from an unlimited stream

Problem Solution Comments Problem This problem was asked by Facebook. Given a stream of elements too large to store in memory, pick a ra...

Posted by chunyang on July 12, 2020

Estimate PI

Problem Solution Problem This problem was asked by Google. The area of a circle is defined as $\pi r^{2}$ . Estimate $\pi$ to 3 decimal pl...

Posted by chunyang on July 11, 2020

At most distinct K

Problem Solution Problem This problem was asked by Amazon. Given an integer k and a string s, find the length of the longest substring tha...

Posted by chunyang on July 10, 2020

Climb up staircase

Problem Solution Reference Problem This problem was asked by Amazon. There exists a staircase with N steps, and you can climb up either ...

Posted by chunyang on July 9, 2020

An autocomplete system

Problem Solution Comments Problem This problem was asked by Twitter. Implement an autocomplete system. That is, given a query string s a...

Posted by chunyang on July 8, 2020

Job scheduler

Problem Solution Reference Problem This problem was asked by Apple. Implement a job scheduler which takes in a function f and an integer...

Posted by chunyang on July 7, 2020

Maximum non-adjacent sum

Problem Solution Problem This problem was asked by Airbnb. Given a list of integers, write a function that returns the largest sum of non-...

Posted by chunyang on July 6, 2020

Xor linked list

Problem Solution Comments Problem This problem was asked by Google. An XOR linked list is a more memory efficient doubly linked list. In...

Posted by chunyang on July 5, 2020