// compile: make data // run: ./data < data.in #include <bits/stdc++.h> using namespace std; #pragma GCC optimize("O3,unroll-loops") #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt") #ifdef LOCAL #include <debug/codeforces.h> #define debug(x...) _debug_print(#x, x); #else #define debug(x...) {}; #endif template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;} #define rep(i,a,b) for(int i=(a);i<(int)(b);++i) #define sz(v) ((int)(v).size()) #define print(...) print_(__VA_ARGS__); #define INTMAX (int)(9223372036854775807) #define INF (int)(1152921504606846976) #define double long double #define int long long #define MAXN 200010 #define P 1000000007 constexpr long long safe_mod(long long x, long long m) { x %= m; if (x < 0) x += m; return x; } constexpr std::pair<long long, long long> inv_gcd(long long a, long long b) { a = safe_mod(a, b); if (a == 0) return {b, 0}; long long s = b, t = a; long long m0 = 0, m1 = 1; while (t) { long long u = s / t; s -= t * u; m0 -= m1 * u; auto tmp = s; s = t; t = tmp; tmp = m0; m0 = m1; m1 = tmp; } if (m0 < 0) m0 += b / s; return {s, m0}; } long long inv_mod(long long x, long long m) { assert(1 <= m); auto z = inv_gcd(x, m); assert(z.first == 1); return z.second; } void solve() { int n, m; cin >> n >> m; vector<int> a(n); vector<pair<int, int>> f; rep(i, 0, n) cin >> a[i]; sort(a.begin(), a.end()); f.push_back({a[0], 1}); rep(i, 1, n) { if (a[i] == a[i-1]) ++f.back().second; else f.push_back({a[i], 1}); } n = sz(f); int ans = 0; auto calc = [&](int l, int r) { int sum = 0; int mux = 1; rep(i, l, l+m) mux = (mux * f[i].second) % P; sum += mux; for (int i = l+1; i+m-1 <= r; ++i) { mux = (mux * f[i+m-1].second) % P; mux = (mux * inv_mod(f[i-1].second, P)) % P; sum = (sum + mux) % P; } return sum; }; int l = 0, r = 0; while (l < n) { while (r+1 < n && f[r+1].first == f[r].first+1) ++r; if (r-l+1 < m) { l = ++r; continue; } ans = (ans + calc(l, r)) % P; l = ++r; } cout << ans << endl; } int32_t main() { ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); int _; cin >> _; while (_--) solve(); return 0; }
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