// author : daohuyenchi
#ifdef LOCAL
#include "D:\C++ Submit\debug.h"
#else
#define debug(...)
#endif
#include <bits/stdc++.h>
using namespace std;
#define ull unsigned long long
#define db double
#define i32 int32_t
#define i64 int64_t
#define ll long long
//
#define fi first
#define se second
// #define int long long // consider carefully
//
#define pii pair <int, int>
#define pll pair <ll, ll>
#define PAIR make_pair
#define TUP make_tuple
// TIME IS LIMITED ...
#define rep(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define repd(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define repv(v, H) for(auto &v: H)
// REFLECT ON THE PAST ...
#define RESET(c, x) memset(c, x, sizeof(c))
#define MASK(i) (1LL << (i))
#define BIT(mask, i) (((mask) >> (i)) & 1LL)
#define ONBIT(mask, i) ((mask) | (1LL << (i)))
#define OFFBIT(mask, i) ((mask) &~ (1LL << (i)))
#define COUNTBIT __builtin_popcountll
// 30 / 1 / 2024 ? love is zero... start from zero
#define vi vector <int>
#define vll vector <ll>
#define Lower lower_bound
#define Upper upper_bound
#define all(v) (v).begin(), (v).end()
#define special(H) (H).resize(distance(H.begin(), unique(all(H))))
//
#define sp ' '
#define nl '\n'
#define EL { cerr << '\n'; }
#define yes "YES"
#define no "NO"
#define Log2(n) (63 - __builtin_clzll(n))
#define left __left__
#define right __right__
#define lps(id) ((id) << 1)
#define rps(id) ((id) << 1 | 1)
//____________________________________________________________________
template <class X, class Y> bool maximize(X &a, const Y &b)
{ if(a < b) return a = b, true; else return false; }
template <class X, class Y> bool minimize(X &a, const Y &b)
{ if(a > b) return a = b, true; else return false; }
template <class... T>
void print(T&&... n)
{ using exp = int[]; exp{ 0, (cerr << n << sp, 0)... }; cerr << nl; }
template <class T, class... C>
void assign(int n, T v, C&&... a)
{ using e = int[]; e { (a.assign(n, v), 0)...}; }
template <class... C>
void resize(int n, C&&... a)
{ using e = int[]; e { (a.resize(n), 0)...}; }
template <class T>
using vector2d = vector<vector<T>>;
template <class T>
using vector3d = vector<vector2d<T>>;
template <class T> int ssize(T &a) { return (int) a.size(); }
//____________________________________________________________________
mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());
const long long MOD = 1000000007;
// const int MOD[2] = {1000000009, 998244353};
template<class X> void modmize(X &x, long long cur_Mod = MOD) {
if(x >= cur_Mod) x -= cur_Mod;
if(x < 0) x += cur_Mod;
}
int mod_plus(int A, int B) { modmize(A += B); return A; }
const long long oo = 1e18 + 7;
const long long LINF = 1e18 + 7;
const int IINF = 2e9;
const int nmax = 2e5 + 10;
const int MAX = 1e6;
const int base = 311;
const double eps = 1e-6;
const int block = 500;
static const double PI = acos(-1.0);
//____________________________________________________________________
int n;
int h[nmax];
struct Fenwick {
vector <int> bit;
int Lim;
Fenwick() {}
Fenwick(int _n) {
bit.assign(_n + 1, 0);
Lim = _n;
}
void Assign(int _n) {
bit.assign(_n + 1, 0);
Lim = _n;
}
void Init() {
rep (i, 1, Lim) {
bit[i] = 0;
}
}
void upd(int i, int val) {
for (; i <= Lim; i += i & -i) bit[i] += val;
}
int get_pt(int i) {
int cur = 0;
for (; i > 0; i -= i & -i) cur += bit[i];
return cur;
}
int get_rn(int l, int r) {
return get_pt(r) - get_pt(l - 1);
}
} ;
void tintingyn()
{
cin >> n;
rep (i, 1, n) {
cin >> h[i];
}
vector <int> ord(n + 1);
rep (i, 1, n) {
ord[i] = i;
}
sort(ord.begin() + 1, ord.begin() + n + 1, [&] (int x, int y) {
return h[x] < h[y];
}) ;
ll ans = 0;
Fenwick fen(n);
rep (_i, 1, n) {
int i = ord[_i];
int j = _i;
for (; j < n; ) {
if (h[ord[j + 1]] == h[i]) ++j;
else break;
}
rep (t, _i, j) {
int p = ord[t];
ans += (ll) fen.get_rn(1, p - 1) * fen.get_rn(p + 1, n);
}
rep (t, _i, j) {
int p = ord[t];
fen.upd(p, 1);
}
_i = j;
}
cout << ans << nl;
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//________________________________________________________________
#define TASK "1"
if(fopen(TASK".inp", "r"))
{ freopen(TASK".inp", "r", stdin); freopen(TASK".out", "w", stdout); }
//________________________________________________________________
// CODE FROM HERE ...!
int num_test = 1;
// cin >> num_test;
while(num_test--) {
tintingyn();
}
cerr << '\n' << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << " s\n" << nl;
return 0;
}
컴파일 시 표준 에러 (stderr) 메시지
Mountains.cpp: In function 'int main()':
Mountains.cpp:224:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
224 | { freopen(TASK".inp", "r", stdin); freopen(TASK".out", "w", stdout); }
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Mountains.cpp:224:47: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
224 | { freopen(TASK".inp", "r", stdin); freopen(TASK".out", "w", stdout); }
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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