Submission #1308521

#	Time	Username	Problem	Language	Result	Execution time	Memory
1308521		Mahog	Cryptography (NOI20_crypto)	C++20	100 / 100	444 ms	19236 KiB

Crypto

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

typedef long long ll;
const int MAX = 3e5 + 2;
const int MOD = 1e9 + 7;
ll a[MAX], fact[MAX], n;

void solve() {
    cin >> n;
    ordered_set st;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        st.insert(a[i]);
    }
    fact[0] = 1;
    for (int i = 1; i <= n; i++) fact[i] = fact[i - 1] * i % MOD;
    ll res = 0;
    for (int i = 1; i <= n; i++) {
        int temp = st.order_of_key(a[i]);
        res = (res + fact[n - i] * temp) % MOD;
        st.erase(a[i]);
    }
    cout << (res + 1) % MOD;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
}

• 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