Connect 4

The game Connect 4 is played on a vertical grid of six rows and seven columns as illustrated in Figure 1. Players take turns dropping checkers into columns of the board. Each checker falls to the row immediately above the last which was played in that column. Initial drops in any column land in the bottom row. The object of the game is to create a board configuration in which four of a player's pieces are in a contiguous horizontal, vertical or diagonal () line.

 
Figure 1:  The Connect 4 Playing Board