//////////////////////////////////////// /// tu3 pro-con template /// //////////////////////////////////////// #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; //// MACRO //// #define countof(a) (sizeof(a)/sizeof(a[0])) #define REP(i,n) for (int i = 0; i < (n); i++) #define RREP(i,n) for (int i = (n)-1; i >= 0; i--) #define FOR(i,s,n) for (int i = (s); i < (n); i++) #define RFOR(i,s,n) for (int i = (n)-1; i >= (s); i--) #define pos(c,i) c.being() + (i) #define allof(c) c.begin(), c.end() #define aallof(a) a, countof(a) #define partof(c,i,n) c.begin() + (i), c.begin() + (i) + (n) #define apartof(a,i,n) a + (i), a + (i) + (n) typedef unsigned int uint; typedef long long llong; typedef unsigned long long ullong; #define long long long #define EPS 1e-9 #define INF (1L << 28) #define LINF (1LL << 60) #define PREDICATE(t,a,exp) [&](const t & a) -> bool { return exp; } #define COMPARISON_T(t) bool(*)(const t &, const t &) #define COMPARISON(t,a,b,exp) [&](const t & a, const t & b) -> bool { return exp; } #define CONVERTER(TSrc,t,TDest,exp) [&](const TSrc &t)->TDest { return exp; } inline int sign_of(double x) { return abs(x) < EPS ? 0 : x > 0 ? 1 : -1; } inline bool inRange(int val, int min, int max) { return val >= min && val < max; } inline bool inRange(double val, double min, double max) { return val - min > -EPS && val - max < EPS; } inline bool inRange(int x, int y, int W, int H) { return x >= 0 && x < W && y >= 0 && y < H; } // W,H含まない template struct vevector : public vector> { vevector(int n = 0, int m = 0, const T &initial = T()) : vector>(n, vector(m, initial)) { } }; template struct vevevector : public vector> { vevevector(int n = 0, int m = 0, int l = 0, const T &initial = T()) : vector>(n, vevector(m, l, initial)) { } }; template struct vevevevector : public vector> { vevevevector(int n = 0, int m = 0, int l = 0, int k = 0, const T &initial = T()) : vector>(n, vevevector(m, l, k, initial)) { } }; //// i/o helper //// namespace std { template inline istream & operator >> (istream & in, pair &p) { in >> p.first >> p.second; return in; } template inline ostream & operator << (ostream &out, const pair &p) { out << p.first << " " << p.second; return out; } } template T read() { T t; cin >> t; return t; } template vector read(int n) { vector v; v.reserve(n); REP(i, n) { v.push_back(read()); } return v; } template vevector read(int n, int m) { vevector v; REP(i, n) v.push_back(read(m)); return v; } template vector readjag() { return read(read()); } template vevector readjag(int n) { vevector v; v.reserve(n); REP(i, n) v.push_back(readjag()); return v; } template struct iter_pair_t { T beg, end; }; template iter_pair_t iter_pair(T beg, T end) { return iter_pair_t{beg, end}; } template ostream & operator << (ostream &out, const iter_pair_t &v) { std::copy(v.beg, v.end, ostream_iterator(out, " ")); return out; } template ostream & operator << (ostream &out, const vector &v) { return out << iter_pair(begin(v), end(v)); } template ostream & operator << (ostream &out, const set &v) { return out << iter_pair(begin(v), end(v)); } template ostream & operator << (ostream &out, const map &v) { return out << iter_pair(begin(v), end(v)); } struct _Reader { istream &cin; template _Reader operator ,(T &rhs) { cin >> rhs; return *this; } }; struct _Writer { ostream &cout; bool f{ false }; template _Writer operator ,(const T &rhs) { cout << (f ? " " : "") << rhs; f = true; return *this; } }; #define READ(t,...) t __VA_ARGS__; (_Reader{cin}), __VA_ARGS__ #define WRITE(...) (_Writer{cout}), __VA_ARGS__; cout << '\n' #define DEBUG(...) (_Writer{cerr}), __VA_ARGS__; cerr << '\n' void solve(); int main() { //cin.tie(0); //ios_base::sync_with_stdio(false); //cout << setprecision(std::numeric_limits::max_digits10); solve(); return 0; } /// 2分セグメント木。RMQとかが解ける。 struct SegTree { typedef int T; int size; vector tree; unsigned msb(unsigned v) { REP(i, 5) v |= v >> (1 << i); return (v >> 1) + 1; } SegTree(int count, T initialFill = INF) : size(msb(count - 1) << 1) , tree(size * 2) { fill(partof(tree, size, size), initialFill); rebuild(); } // []を使うと更新されないのでrebuildすること。数が少なければupdateの方がよい。 T& operator[](int i) { return tree[i + size]; } void rebuild() { RREP(i, size) { tree[i] = tree[i * 2] + tree[i * 2 + 1]; } } void update(int index, T value) { tree[index + size] = value; for (int i = (index + size) / 2; i > 0; i /= 2) tree[i] = tree[i * 2] + tree[i * 2 + 1]; } T query(int s, int e, int i, int l, int r, T value) { if (r <= s || e <= l) return value; if (s <= l && r <= e) return value + tree[i]; value = query(s, e, i * 2, l, (l + r) / 2, value); value = query(s, e, i * 2 + 1, (l + r) / 2, r, value); return value; } T query(int start, int count, T initialValue) { return query(start, start + count, 1, 0, size, initialValue); } }; //////////////////// /// template end /// //////////////////// void solve() { //freopen("input.txt", "r", stdin); READ(int, N); auto A = read(N); DEBUG(N); // compress //map MP; int M; { map comp; for (auto a : A) { comp[a] = 0; } int i = 0; for (auto &p : comp) { p.second = i++; } for (auto &a : A) { /* MP[comp[a]] = a; */ a = comp[a]; } M = comp.size(); } DEBUG(M); vector lel(N), grl(N); vector ler(N), grr(N); vector l(M), r(M); { SegTree tree(M, 0); REP(i, N) { auto a = A[i]; tree.update(a, tree[a] + 1); lel[i] = tree.query(0, a, 0); grl[i] = tree.query(a + 1, N - a - 1, 0); } } { SegTree tree(M, 0); RREP(i, N) { auto a = A[i]; tree.update(a, tree[a] + 1); ler[i] = tree.query(0, a, 0); grr[i] = tree.query(a + 1, N - a - 1, 0); } } REP(i,N) { r[A[i]]++; } r[A[0]]--; l[A[0]]++; llong ans = 0; llong minus = l[A[0]] * r[A[0]]; FOR(i, 1, N-1) { minus -= (llong)l[A[i]] * r[A[i]]; r[A[i]]--; ans += (llong)lel[i] * ler[i]; ans += (llong)grl[i] * grr[i]; //int minu = 0; //DEBUG("loop: ", A_[i]); //REP(j, M) //{ // if (j != A[i]) // { // minu += l[j] * r[j]; // if (l[j] * r[j]) // { // DEBUG("", MP[j], ":", l[j], "*", r[j], "=", l[j] * r[j]); // } // } // //} //DEBUG("-->", minu); //DEBUG("-->", minus); ans -= minus; l[A[i]]++; minus += (llong)l[A[i]] * r[A[i]]; } WRITE(ans); }