Problem 15

Problem Statement :Problem15

Starting in the top left corner of a 22 grid, there are 6 routes (without backtracking) to the bottom right corner.

How many routes are there through a 2020 grid?

Algorithm:

• We need 40 steps to reach to the bottom right corner
• We have a choice of 2 directions Down and Right
• Fill any 20 steps with D the remaining will be filled with R
• The straight of answer is 40C20 ie (40!/(20!*20!))