a. Pseudo code for time complexity $O(n\log n)$ :
for(i=1; i<=n; i++)
{
if (binary_search( x- A[i] ) // O(logn)
return true;
}
return false;
b. Pseudo code for time complexity $O(n)$ :
for( k=1, l=n; k<l ; )
{
temp =A[k] + A[l];
if (temp== x)
return true;
else if(temp > x)
l--;
else
k++;
}
return false;