Counting Triangles

/*
* @Author: Kabid
* @Date:   {{create_time}}
* @Last Modified by:   Kabid
* @Last Modified time: 2021-02-18 18:02:31
*/
#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define dbug cerr<<"HERE"<<endl;
//===============Declaration=======================================
int t;
ll i, j;     //iterators
ll n, k , p, m, c, x; //variables;
ll mx = LLONG_MIN, mn = LLONG_MAX;      // max min
int a [20001];

int bs(int l, int r, int xx) {
    //cerr << "HERE" << endl;
    int mid = (l + r) / 2;
    while(l<=r){
        //cerr<<mid<<endl;
        if(a[mid]<xx)
            return bs (l+1,r,xx);
        else if(a[mid]>xx)
            return bs (l, mid-1, xx);
        else return mid;
    }
    //cerr<<"--------+"<<r-1<<endl;
    return l;
}
void solve();
int main() {


    cin >> t; x = t;
    while (t-- ) {
        solve();
    }
    return 0;

}


void solve() {
    cin >> n; int ct = 0;
    for (i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a, a + n);
    for (i = 0; i < n - 2; i++) {
        for (j = i + 1; j < n - 1; j++) {

            ct += bs(j + 1, n - 1, a[i] + a[j]) - j -1;         //cout<<a[i]<<' '<<a[j]<<' '<<k<<' '<<j<<endl;

        }
    }
    cout << "Case " << x - t << ": " << ct << endl;
}

/**
3
5
3 12 5 4 9
6
1 2 3 4 5 6
4
100 211 212 121

**/