Latest posts

A list of special data structures

We provide a list of data structures that serve specific purposes when solving LeetCode problems.

State space representation of IIR filters

We show how to express a discrete-time infinite impulse response (IIR) filter in state-space form.

Direct Form I and Direct Form II

We derive the Direct Form I and Direct Form II implementations of a discrete-time infinite impulse response (IIR) filter.

Squaring the square

We prove that every square can be partitioned into $n$ squares for every $n \geq 6$.

Fencepost errors

We describe what fencepost errors are, how to avoid them, and provide a precise derivation for why they occur.