Submission #596572

#	Time	Username	Problem	Language	Result	Execution time	Memory
596572		AdamGS	Cryptography (NOI20_crypto)	C++17	100 / 100	390 ms	25316 KiB

Crypto

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define all(a) a.begin(), a.end()
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const ll MOD=1e9+7, LIM=3e5+7;
int T[LIM], S[LIM], tr[4*LIM], N=1;
ll sil[LIM];
map<int,int>mp;
void upd(int v) {
  for(v+=N; v; v/=2) --tr[v];
}
ll cnt(int l, int r) {
  l+=N; r+=N;
  ll ans=tr[l];
  if(l!=r) ans+=tr[r];
  while(l/2!=r/2) {
    if(l%2==0) ans+=tr[l+1];
    if(r%2==1) ans+=tr[r-1];
    l/=2; r/=2;
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(0); cin.tie(0);
  sil[0]=1;
  for(ll i=1; i<LIM; ++i) sil[i]=(sil[i-1]*i)%MOD;
  int n;
  cin >> n;
  while(N<n) N*=2;
  rep(i, n) {
    cin >> T[i];
    S[i]=T[i];
    tr[N+i]=1;
  }
  for(int i=N-1; i; --i) tr[i]=tr[2*i]+tr[2*i+1];
  sort(S, S+n);
  rep(i, n) mp[S[i]]=i;
  ll ans=1;
  rep(i, n) {
    ll x=cnt(0, mp[T[i]]);
    upd(mp[T[i]]);
    ans=(ans+sil[n-i-1]*(x-1))%MOD;
  }
  cout << ans << '\n';
}

• 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