def fibR(n):
    if n==0:
        return 0
    elif n==1:
        return 1
    else:
        return fibR(n-1) + fibR(n-2)
        

def fibI(n):
    if n==0:
        return 0
    elif n==1:
        return 1
    else:
        previousE = 0
        nextE = 1
        
        for i in range(n-1):
            s = previousE + nextE
        
            previousE = nextE
            nextE = s
            
        return s
        

def fibRM(n, memo):
    if n in memo:
        return memo[n]
    else:
        r = fibRM(n-1, memo) + fibRM(n-2, memo)
        memo[n] = r
        return r
        
    
#r = fibR(37)
#print(r)

r = fibI(670)
print(r)


memo = {0: 0, 1: 1}

r = fibRM(670, memo)
print(r)

print(memo)

'''

czas:
39 -> 20
40 -> 30
41 -> 45
42 -> 70
43 -> 110
44 -> 170
45 -> 250
46 -> 380
47 -> 


4 -> 9
5 -> 15
6 -> 25
7 -> 25 + 13 -> 38

fib(4)--+
        |
        +--------------------------------------+
        |                                      |
      fib(3)--+                             fib(2)--+
              |                                     |
              +-------------------------+           +---------+
              |                         |           |         |
             fib(2)--+               fib(1)       fib(1)     fib(0)
                     |
                     +------+
                     |      |
                 fib(1)   fib(0)
                 
fib(5): 9 5 1 +/- 15    

fib(6): 15 + 9 + 1
        
'''