Project Euler - 002

icymirror

Problem 2:
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

问题2:
斐波那契数列中的每一项都是由它之前两项求和得到的。当以1和2开始时，开始10项是：1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ......
现在，把此数列中的数值不超过4000000的项中的偶数求和，结果是多少？

代码：

1. package main
   
2. 
   
3. import (
   
4.         "fmt"
   
5. )
   
6. 
   
7. func Problem002(scope int) int {
   
8.         sum := 0
   
9. 
   
10.         first := 1
    
11.         second := 2
    
12.        
    
13.         for {
    
14.                 if (second > scope) {
    
15.                         break
    
16.                 }
    
17.                
    
18.                 sum = sum + second
    
19. 
    
20.                 first, second = first + second * 2, first * 2 + second * 3
    
21.         }
    
22.        
    
23.         return sum
    
24. }
    
25. 
    
26. func main() {
    
27.         fmt.Println("Problem 002 result: ", Problem002(4000000))
    
28. }

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ba_du_co

拿来练练手。
4613732

1. #!perl6
   
2. my $n = 4000000;
   
3. say [+] (1, 2, *+* ...^ * > $n).grep: * %% 2

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