Project Euler #2 Even Fibonacci numbers.cpp

#include<iostream>
using namespace std;

int main(){
    int t,i=0;
    unsigned long long n=40000000000000000,sum=0,a=0,b=1,c,d,e[50];
    while(1){
        c=b;
        b=a+b;
        if(b>n) break;
        a=c;      
        if(b%2==0) e[i++]=b;
     }    
    cin>>t;
    while(t--){
     sum=0;
     int j=0;
     cin>>n;
     while(e[j]<=n && j<i) sum+=e[j++] ;       
     cout<<sum<<endl;
    }   
    return 0;
}