哪个算法给大家看看？

[zdqsm]

看题如下：

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, ...

Find the sum of all the even-valued terms in the sequence which do not exceed four million.

[僵哥]

int pre_i = 1,i = 2,sum = 3;
while sum < 4000000 
 begin
   i += pre_i ;
   pre_i = i - pre_i;
   sum += i;
 end;

[僵哥]

应该是 <= 4000000

[night_elf_1020]

应该是 1，1，2，3，5，8，。。。。。
所以序数是三倍数的位置上都是偶数
下面用循环就可以了

int Fn_2=1;
int Fn_1=1;
int Fn=F1+F2;
int sum=0;
bool True=1;
while(True)
{
if(sum<=4000000)
break;
else
sum+=Fn;
Fn_2=Fn+Fn_1;
Fn_1=Fn-2+Fn;
Fn=Fn_1+Fn_2;

}


cout<<sum<<endl;

[zdqsm]

僵哥：好，
你这样算的话，结果还是回超过4000000，不对啊

[僵哥]

int pre_i = 1,i = 2,sum = 3;
while sum <= 4000000
begin
i += pre_i ;
pre_i = i - pre_i;
if ((sum + i) > 4000000) break;
sum += i;

end;

[僵哥]

现在才发现,彻底地晕了,C++/Delphi都分不清楚了.

int pre_i = 1,i = 2,sum = 3; 
while (1) 
{
  i += pre_i ; 
  pre_i = i - pre_i; 
  if ((sum + i) > 4000000) break; 
  sum += i; 
} 

[yubinbrokenheart]

clear
clc

Fibonacci(1)=1;
Fibonacci(2)=2;
sum=1;
i=3;

while 1
Fibonacci(i)=Fibonacci(i-1)+Fibonacci(i-2);

if mod(Fibonacci(i),2)~=0
if sum+Fibonacci(i)>=4000000
break;
else
sum=sum+Fibonacci(i);
end
end
i=i+1;
end

[zdqsm]

按照你们算法
算的结果都不对
怎么回事？