Submission #958029

#	Time	Username	Problem	Language	Result	Execution time	Memory
958029		Zena_Hossam	Cryptography (NOI20_crypto)	C++14	100 / 100	541 ms	52840 KiB

Crypto

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#define ll long long
using namespace std;
namespace __gnu_pbds
{
typedef tree<ll,
        null_type,
        less_equal<ll>,
        rb_tree_tag,
        tree_order_statistics_node_update> ordered_set;
}
using namespace __gnu_pbds;
#define fi ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//#define ll double

#define ll1 long long
#define F first
#define S second
#define sz size()
#define all(s) s.begin(),s.end()
#define all1(s) s.rbegin(),s.rend()
ll mod=1e9+7;
int main()
{
    fi
    //freopen("stdin.in","r",stdin);freopen("stdout.out","w",stdout);
    //cin>>T;ll oo=0;
    ll n;
    cin>>n;
    map<ll,ll>d;
    ll m[n+5]={};ll dd[n+5]={};
    ll o=1;
    for(ll i=1;i<=n;i++){
        o=(i*o)%mod;
        m[i]=o;
    }
    ll arr[n],a[n];
    for(ll i=0;i<n;i++){

        cin>>a[i];
        arr[i]=a[i];
    }
    sort(a,a+n);
    for(ll i=0;i<n;i++){
        d[a[i]]=i+1;
    }
    for(ll i=1;i<=n;i++){
        dd[d[arr[i-1]]]=i;
    }
    ll k[n+5]={};ll c=0;
    ordered_set q;
    for(ll i=1;i<=n;i++){
        //cout<<i-q.order_of_key(dd[i])-1<<" ";
        c+=((m[(n-dd[i])]%mod)*((i-1-q.order_of_key(dd[i]))%mod))%mod;q.insert(dd[i]);
    }cout<<(c+1)%mod;
}

Compilation message (stderr)

Crypto.cpp: In function 'int main()':
Crypto.cpp:52:8: warning: unused variable 'k' [-Wunused-variable]
   52 |     ll k[n+5]={};ll c=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