With great $F_{n}$ comes great runtime

Computer Science Level 3

Let $F_{n}$ denotes the $n^\text{th}$ Fibonacci number .

Find the sum of odd-digits of $\displaystyle F_{1000}$ .

As an explicit example, sum of odd-digits of $128974402103=1+8+7+4+2+0=22$

The answer is 508.

1 solution

Pranjal Jain
Jun 2, 2016

fibs=[0,1]
for i in range(1000):
    fibs.append(fibs[-1]+fibs[-2])
x=str(fibs[1000])
ans=sum(ord(x[i])-ord('0') for i in range(0,len(x),2))
print(ans)

@Pranjal Jain , Can you please present a solution in C/C++, I can't make out of this. ( I tried in C, but the time limit was exceeded!)

Kunal Gupta - 4 years, 11 months ago

With great F n F_{n} F n ​ comes great runtime

The answer is 508.

1 solution

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With great $F_{n}$ comes great runtime