제출 #691275

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
691275		ghostwriter	Cryptography (NOI20_crypto)	C++17	100 / 100	120 ms	8112 KiB

Crypto

#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 ins insert
#define ers erase
#define lb lower_bound
#define ub upper_bound
#define bg begin
#define ed end
#define ft front
#define bk back
#define sz(x) (int)x.size()
#define all(x) (x).bg(), (x).ed()
#define mtp make_tuple
#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); }
const int M = 1e9 + 7;
const int N = 3e5 + 5;
int n, p[N], s[N], f[N], f1[N];
int getp(int x) { return lb(s + 1, s + 1 + n, x) - s; }
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; }
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 >> p[i];
    FOR(i, 1, n) s[i] = p[i];
    sort(s + 1, s + 1 + n);
    int rs = 1;
    f1[0] = 1;
    FOR(i, 1, n) f1[i] = 1LL * f1[i - 1] * i % M;
    FOR(i, 1, n) {
        int cur = getp(p[i]), sm = cur - 1 - get(cur - 1);
        (rs += 1LL * sm * f1[n - i] % M) %= M;
        upd(cur, 1);
    }
    cout << rs;
    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 9 / 9
• Subtask 3: 10 / 10
• Subtask 4: 11 / 11
• Subtask 5: 21 / 21
• Subtask 6: 13 / 13
• Subtask 7: 19 / 19
• Subtask 8: 12 / 12