Submission #973232

#	Time	Username	Problem	Language	Result	Execution time	Memory
973232		njoop	Cryptography (NOI20_crypto)	C++17	100 / 100	328 ms	25076 KiB

Crypto

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
#define ll long long

using namespace __gnu_pbds;
using namespace std;

int n, in, ord[300010], idx;
ll fac[300010], mod = 1e9+7, ans;
vector<pair<int, int>> v;

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

ordered_set s;

int main() {
    cin.tie(0)->sync_with_stdio(0);
    fac[0] = 1;
    for(int i=1; i<300010; i++) {
        fac[i] = i*fac[i-1];
        fac[i] %= mod;
    }
    cin >> n;
    for(int i=1; i<=n; i++) {
        cin >> in;
        v.push_back({in, i});
    }
    sort(v.begin(), v.end());
    for(int i=0; i<v.size(); i++) {
        ord[v[i].second] = i;
    }
    for(int i=1; i<=n; i++) {
        idx = s.order_of_key(ord[i]);
        ans += ((ord[i]-idx)*fac[n-i])%mod;
        ans %= mod;
        s.insert(ord[i]);
    }
    cout << (ans+1)%mod;
    return 0;
}

Compilation message (stderr)

Crypto.cpp: In function 'int main()':
Crypto.cpp:30:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |     for(int i=0; i<v.size(); i++) {
      |                  ~^~~~~~~~~

• 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