Submission #739899

#	Time	Username	Problem	Language	Result	Execution time	Memory
739899		MODDI	Cryptography (NOI20_crypto)	C++14	100 / 100	855 ms	43220 KiB

Crypto

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
  
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define pb push_back
#define mp make_pair
typedef long long ll;
typedef pair<long long, long long> pll;
typedef pair<int,int> pii;
typedef vector<long long> vl;
typedef vector<int> vi;
int n;
vl arr, p;
const int mod = 1e9 + 7;
ll power[300100];
int main(){
	cin>>n;
	arr.resize(n);
	for(int i = 0; i < n; i++){
		cin>>arr[i];
		p.pb(arr[i]);
	}
	memset(power, 0, sizeof power);
	power[1] = 1;
	for(int i =2; i < n; i++){
		power[i] = i * power[i-1];
		power[i] %= mod;
	}
	sort(p.begin(), p.end());
	map<ll, ll> lower;
	for(int i = 0; i < n; i++)
		lower[p[i]] = i;
		
	int ele = n - 1;
	ll ans = 0;
	ordered_set o_set;
	for(int i = 0; i < n; i++){
		ll here = lower[arr[i]] - o_set.order_of_key(arr[i]);
//		cout<<here<<" "; 
//		cout<<here<<" "<<power[ele]<<" "<<ele<<endl;
		ans += (here * power[ele]) % mod;
		ans %= mod;
		ele--;
		o_set.insert(arr[i]);
	}
//	cout<<endl;
	cout<<(ans+1)%mod<<endl;
	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