For an NxN square it takes (2N - 2) steps to move from the upper left corner to bottom right corner.
Of these steps, half must be right and half must be down (N - 1 in each direction).
Knowing this, we can look at it as a string permutation or how many ways can you write "RRRDDD", etc.
(this would be for N = 4, "RRDD" for N = 3 and so on).
Now we just have to count the number of permutations for this string which in terms of N will be (2N - 2)!/((N - 1)!(N - 1)!).
These numbers match up....
2, 2
3, 6
4, 20
5, 70
6, 252
7, 924
8, 3432
Read full article from GoHired: robot standing at first cell of an M*N matrix. It can move only in two directions, right and down. In how many ways, it can reach to the last cell i.e. (M, N) Code it
