(n)
return arr[-1]
:type n: int
    :rtype: int
:type n: int
    :rtype: int
: type n : int : rtype : int
def climb_stairs(n):
    """
    :type n: int
    :rtype: int
    """
    arr = [1, 1]
    for i in range(2, n + 1):
        arr.append(arr[-1] + arr[-2])
    return arr[-1]
def climb_stairs ( n ) : arr = [ 1 , 1 ] for i in range ( 2 , n + 1 ) : arr . append ( arr [ - 1 ] + arr [ - 2 ] ) return arr [ - 1 ]