shangshang-wang

def count_sets_dp(arr, total):
	mem = {}
	return dp(arr, total, len(arr)-1, mem)

def dp(arr, total, i, mem):
	key = str(total) + ":" + str(i)
	if key in mem: return mem[key]
	if total == 0: return 1
	else if total < 0: return 0
	else if i < 0: return 0

shangshang-wang

def fib_bottom_up(n):
    if n == 1 or n == 2:
        return 1
    bottom_up = [None] * (n+1)
    bottom_up[1] = 1
    bottom_up[2] = 1
    for i in range(3, n+1):
        bottom_up[i] = bottom_up[i-1] + bottom_up[i-2]
    return bottom_up[n]