Submission #687570

#	Time	Username	Problem	Language	Result	Execution time	Memory
687570		ksjsjsjsjsjsjs	Mountains (NOI20_mountains)	C++14	100 / 100	302 ms	12496 KiB

Mountains

#include <bits/stdc++.h>
using namespace std;
#define st first
#define nd second
#define pb push_back
#define pf push_front
#define _pb pop_back
#define _pf pop_front
#define lb lower_bound
#define ub upper_bound
#define ins insert
#define ers erase
#define bg begin
#define ed end
#define ft front
#define bk back
#define mtp make_tupl
#define sz(x) (int)(x).size()
#define all(x) (x).bg(), (x).ed()
#define ll long long
#define ull unsigned long long
#define db double
#define ldb long double
#define str string
#define pi pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vll vector<ll>
#define vpi vector<pi>
#define vpll vector<pll>
#define FOR(i, l, r) for (int i = (l); i <= (r); ++i)
#define FOS(i, r, l) for (int i = (r); i >= (l); --i)
#define FRN(i, n) for (int i = 0; i < (n); ++i)
#define FSN(i, n) for (int i = (n) - 1; i >= 0; --i)
#define EACH(i, x) for (auto &i : (x))
#define WHILE while
template<typename T> T gcd(T a, T b) { WHILE(b) { a %= b; swap(a, b); } return a; }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
#define file "TEST"
mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
ll rand(ll l, ll r) { return uniform_int_distribution<ll>(l, r)(rd); }
struct Fenwick {
    int n;
    vi f;
    Fenwick() {}
    Fenwick(int n) : n(n) { f.resize(n + 1, 0); }
    void upd(int pos, int v) { for (int i = pos; i <= n; i += (i & -i)) f[i] += v; }
    int get(int pos) { int rs = 0; for (int i = pos; i > 0; i -= (i & -i)) rs += f[i]; return rs; }
};
const int N = 3e5 + 5;
int n;
ll h[N];
void compress() {
    vll v;
    FOR(i, 1, n) v.pb(h[i]);
    sort(all(v));
    FOR(i, 1, n) h[i] = lb(all(v), h[i]) - v.bg() + 1;
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//    freopen(file".inp", "r", stdin);
//    freopen(file".out", "w", stdout);
    cin >> n;
    FOR(i, 1, n) cin >> h[i];
    compress();
    Fenwick f1(n), f2(n);
    FOR(i, 1, n) f2.upd(h[i], 1);
    ll rs = 0;
    FOR(i, 1, n) {
        f2.upd(h[i], -1);
        rs += 1LL * f1.get(h[i] - 1) * f2.get(h[i] - 1);
        f1.upd(h[i], 1);
    }
    cout << rs;
//    cerr << "\nTime: " << setprecision(5) << fixed << (ldb)clock() / CLOCKS_PER_SEC << "ms\n";
    return 0;
}

• Subtask 1: 2 / 2
• Subtask 2: 4 / 4
• Subtask 3: 9 / 9
• Subtask 4: 36 / 36
• Subtask 5: 28 / 28
• Subtask 6: 9 / 9
• Subtask 7: 12 / 12