title: Dynamic Programming for sub sum elements in a matrix
body: <p>Given a chess board with 4 rows and <code>n</code> columns. On every cell there's an integer. Given <code>2n</code> discs that part of them, or all of them you can put on a different cell on the board so the total sum is maximal. The only limitation is that 2 discs can't be next to each other vertically or horizontally. How to place the best combination of discs on the board in <code>O(n)</code> using DP ?</p>