I am trying to solve a tricky problem involving a sorted array. Say I have an array of sorted integers (8, 6, 4, 1) and given the value x I need to check the array to see if any two numbers add up to x. This needs to be done in linear time. So far I have come up with this:

```
#include <iostream>
using namespace std;
bool sum(int arr[], int n, int k)
{
int temp1(0), temp2(0);
while (arr[temp1] + arr[temp1 + 1] <= k);
{
if (arr[temp1] + arr[temp1 + 1] == k)
{
return true;
}
if (arr[temp1] + arr[temp1 + 1] < k)
{
temp1 += 1;
}
}
temp2 = temp1 + 1;
for (temp1; temp1 > 0; --temp1)
{
if (arr[temp1] + arr[temp1] == k)
{
return true;
}
}
return false;
}
int main()
{
int list[4] = {8, 6, 4, 1};
bool result = true;
result = sum2(list, 4, 10);
cout << result << endl;
return 0;
}
```

It does not work and I am entirely at loss as to how I may go about getting this problem to work. I know how to do it in quadratic time using two loops, but doing it in linear time is getting to be frustratingly difficult.