Winter - LightOJ

//Make CSP great again
#include <bits/stdc++.h>
#define TASK "TESTCODE"
using namespace std;
const int oo = 1e9, N = 1e5;
int dp[N + 2], a[N + 1], n, k;
void read()
{
    cin >> n >> k;
    dp[n + 1] = 0;
    for (int i = 1; i <= n; ++ i)
    {
        cin >> a[i];
        dp[i] = oo;
    }
    sort(a + 1, a + n + 1);
}
void solve()
{
    for (int i = n; i >= 1; -- i)
    {
        int j = upper_bound(a + i + 1, a + n + 1, a[i] + 2 * k) - a - 1;
        for (int r = j; r >= max(i + 2, j - 3); -- r)
        {
            dp[i] = min(dp[i], dp[r + 1] + 1);
        }
    }
    cout << (dp[1] == oo ? -1 : dp[1]) << '\n';
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (fopen(TASK".INP", "r"))
    {
        freopen(TASK".INP", "r", stdin);
        //freopen(TASK".OUT", "w", stdout);
    }
    int t = 1;
    bool typetest = true;
    if (typetest)
    {
        cin >> t;
    }
    for (int __ = 1; __ <= t; ++ __)
    {
        cout << "Case " << __ <<": ";
        read();
        solve();
    }
}
;