O(N)
d = [0]*100
def fibo(x):
if x == 1 or x == 2:
return 1
if d[x] != 0:
return d[x]
d[x] = fibo(x-1) + fibo(x-2)
return d[x]
print(fibo(99))
d = [0]*100
d[1] = 1
d[2] = 1
n = 99
for i in range(3, n+1):
d[i] = d[i-1] + d[i-2]
print(d[n])