What is Demi doing?

Not Demi, but...

Dynamic programming refers to a methodology that solves problems in an optimal way Usually, when you use a recursive function, you repeat the previously used action Save the results of this task and recycle the data you saved during the repetitive task Used to reduce the number of operations.

For example, when the Fibonacci function is as follows,

int f(int n)
{
    if(n == 0 || n == 1)
        return n;
    else
        return f(n-1) + f(n-2);
}

In order to obtain f(4), the following operation is performed

f(4) = f(3) + f(2)

f(3) = f(2) + f(1)

where f(2) is called twice. An example of dynamic planning is to store the results of f(2) in advance and use the results saved when f(2) is called.