Find number of ways to reach mat [ m - 1 ] [ n - 1 ] from mat [ 0 ] [ 0 ] in a matrix mat [ ] [ ] ]
def countWays ( m , n ) : NEW_LINE INDENT m = m - 1 NEW_LINE n = n - 1 NEW_LINE return ( factorial ( m + n ) // ( factorial ( m ) * factorial ( n ) ) ) NEW_LINE DEDENT