two pointer

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define test int t; cin>>t; for(int cs=1;cs<=t;cs++)
int main()
{

   test
   {
       ll a[100005],c,d,e=0,f,i,j,k,l;
       cin>>c>>d;
       for(i=0;i<c;i++)
       {
           cin>>a[i];
       }
       sort(a,a+c);
       i=0;
       j=c-1;

       while(i<j && i<c && j>=0)
       {
           if((a[i]+a[j])==d)
           {
               e++;
               i++;
               j--;
           }
           else if((a[i]+a[j])<d)
           {
               i+=1;
           }
           else if((a[i]+a[j])>d)
           {
               j-=1;
           }
       }
       cout<<"Case #"<<cs<<": "<<e<<endl;
   }
   return 0;
}