###################################################################### # Starting in the top left corner of a 2×2 grid, and only being able to # move to the right and down, there are exactly 6 routes to the bottom right corner. # # # How many such routes are there through a 20×20 grid? # ###################################################################### # Look at Pascal's triangle ;) # Every row with an odd amount of number contains the solution to any n-sided grid. # This triangle is weird # Solution: 137846528820