func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   using db = long double;   using str = string;   using pi = pair<int, int>;   template <class T>   using V = vector<T>;   template <class T, size_t SZ>   using AR = array<T, SZ>;   using vi = V<int>;   using vb = V<bool>;   using vpi = V<pi>;   const int MOD = 1e9 + 7;   const db EPS = 1e-9;   const ll BIG = 1e18;   template <class T>   bool ckmin(T& a, const T& b) {     return b < a ? a = b, 1 : 0;   }   template <class T>   bool ckmax(T& a, const T& b) {     return a < b ? a = b, 1 : 0;   }   struct mi {     int v;     explicit operator int() const { return v; }     mi() : v(0) {}     mi(ll _v) : v(int(_v % MOD)) { v += (v < 0) * MOD; }   };   mi& operator+=(mi& a, mi b) {     if ((a.v += b.v) >= MOD) a.v -= MOD;     return a;   }   mi& operator-=(mi& a, mi b) {     if ((a.v -= b.v) < 0) a.v += MOD;     return a;   }   mi operator+(mi a, mi b) { return a += b; }   mi operator-(mi a, mi b) { return a -= b; }   mi operator*(mi a, mi b) { return mi((ll)a.v * b.v); }   mi& operator*=(mi& a, mi b) { return a = a * b; }   mi pow(mi a, ll p) {     assert(p >= 0);     return p == 0 ? 1 : pow(a * a, p / 2) * (p & 1 ? a : 1);   }   mi inv(mi a) {     assert(a.v != 0);     return pow(a, MOD - 2);   }   mi operator/(mi a, mi b) { return a * inv(b); }   bool operator==(mi a, mi b) { return a.v == b.v; }   vector<mi> invs, fac, ifac;   void genFac(int SZ) {     invs.resize(SZ), fac.resize(SZ), ifac.resize(SZ);     invs[1] = fac[0] = ifac[0] = 1;     for (int i = (2); i < (SZ); ++i)       invs[i] = mi(-(ll)MOD / i * (int)invs[MOD % i]);     for (int i = (1); i < (SZ); ++i)       fac[i] = fac[i - 1] * i, ifac[i] = ifac[i - 1] * invs[i];   }   mi comb(int a, int b) {     if (a < b || b < 0) return 0;     return fac[a] * ifac[b] * ifac[a - b];   }   const int mx = 100005;   struct Eff {     int n, k;     mi first[mx];     void solve() {       genFac(100005);       cin >> n >> k;       map<int, int> cnt;       int negs = 0;       for (int i = 1; i <= n; i++) {         int A;         cin >> A;         if (A == -1) {           negs++;         } else {           cnt[A]++;         }       }       map<int, mi> all_cnts;       for (auto u : cnt) {         all_cnts[u.second] = mi(0);       }       all_cnts[0] = mi(0);       first[0] = mi(0);       for (int i = 0; i <= n - 1; i++) {         first[i + 1] = mi(-n);         if (i - 1 >= 0) {           first[i + 1] -= mi(i) * mi(k - 1) * first[i - 1];         }         first[i + 1] += first[i] * (mi(n) - 2 * mi(i) + mi(i) * mi(k));         first[i + 1] = first[i + 1] / mi(n - i);       }       vector<mi> k1pows(n + 1, mi(1));       for (int i = 1; i <= n; i++) {         k1pows[i] = k1pows[i - 1] * mi(k - 1);       }       for (auto& u : all_cnts) {         for (int i = 0; i <= negs; i++) {           u.second += first[u.first + i] * mi(comb(negs, i)) * k1pows[negs - i];         }         u.second = u.second / pow(mi(k), negs);       }       mi ans = mi(0);       map<int, int> cnt_cnt;       for (auto u : cnt) {         cnt_cnt[u.second]++;       }       cnt_cnt[0] += (k - int((cnt).size()));       for (auto u : cnt_cnt) {         ans += all_cnts[u.first] * mi(u.second);       }       ans -= (first[n] + mi(k - 1) * first[0]);       cout << ans.v <<   n ;     }   };   int main() {     cin.tie(0)->sync_with_stdio(0);     Eff e;     e.solve();   }   