Submission #1170599

#	Time	Username	Problem	Language	Result	Execution time	Memory
1170599		Bzslayed	Cryptography (NOI20_crypto)	C++20	100 / 100	296 ms	23920 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; 

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

#define ll long long
#define ull unsigned long long
#define llll __int128
#define ld long double
#define pll pair<ll, ll>
#define pii pair<int, int>
#define coutpair(p) cout << p.first << " " << p.second << "|"

template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<class T> using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;

const ll MOD = 1e9+7;

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    ll n; cin >> n;
    ll p[n];
    ordered_set<ll> s;
    for (int i=0; i<n; i++){
        cin >> p[i];
        s.insert(p[i]);
    }
    
    ll pre[n+5];
    pre[0] = 0, pre[1] = 1;
    for (int i=2; i<=n; i++) pre[i] = (pre[i-1]*i)%MOD;

    ll ans = 0;
    for (int i=0; i<n; i++){
        ll x = s.order_of_key(p[i]);
        //cerr << x << "\n";
        ans += x*pre[n-i-1];
        ans %= MOD;

        s.erase(p[i]);
    }
    ans++; ans %= MOD;

    cout << ans;
    
    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