Algorithim for creating a pattern

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C#

algorithm

I would like to know if there is an anlgorithm that could help me solve the following example problem.

First of we have a list of 1 and 0 :
011001010111 of length 12.

Then we have an x number of 1 to inject anywhere in the list, for instance x=3(not necessary to inject all 3).

Lastly we have a number y that checks the list for every y-th element for a 1.

For instance y=4 which means the program in this example before injections will output 2 as 4th element contains a 0 but both 8th and 12th contain a 1.

The Algorith in this example should inject a maximum of 3 1s into the list so that every 4th element would contain as fewer 1 as possible.

A correct answer for this example could look something like this:

(Injecting into list with first index being 1)

 1. Injection at index 7 => list=0110011010111, length=13, output=1.
 2. Injection at index 10 => list=01100110110111, length=14, output=1. 
 3. Injection at index 10 => list=011001101110111, length=15, output=0.

Another correct asnwer can also look like this:  

 1. Injection at index 1 => list=1011001010111, length=13, output=2.
 2. Injection at index 1 => list=11011001010111, length=14, output=3. 
 3. Injection at index 1 => list=111011001010111, length=15, output=0.  
  
Lenght=<10000, x=<50, y=<10000

What I have tried:

So far i have tried a simple aproach that checks for best injections for all injections, meanning that each time i inject i inject at the best possible possition that returns the least amount of 1. I was also told that this can be solved using dynamic programming with a matrix of x * (n/y). So if anyone can point me at the right direction or help me understand the implementation using the matrix would much appreciate it.