Submission #949902

#	Time	Username	Problem	Language	Result	Execution time	Memory
949902		sondos225	Cryptography (NOI20_crypto)	C++17	100 / 100	503 ms	48308 KiB

Crypto

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T>using ordered_set = tree<T,null_type,less_equal<T>,rb_tree_tag,tree_order_statistics_node_update>;//find_by_order(ind);
//order_of_key()
#define int long long
#define fast ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);
#define pb push_back
#define yes "YES"
#define no "NO"
#define bigg INT_MAX
#define debug(x) cout<<(#x)<<" = " <<x<<endl;
#define all(x) x.begin(),x.end()
#define sz size()
#define nn '\n'
#define mms(x,y) memset(x,y,sizeof(x))
#define forr(i,j,n) for (int i=j; i<n; i++)
#define forn(i,j,n) for (int i=j; i>n; i--)
#define fi first
#define se second
#define la "LA"
#define cinn(x,y) for(int i=0; i<y; i++) cin>>x[i];
#define pii pair<int,int>
//
//int fact(int x)
//{
//    int w=1;
//    forr(i,1,x+1) w*=i;
//}
signed main()
{
//    #ifndef LOCAL
//    freopen("lifeguards.in","r",stdin);
//    freopen("lifeguards.out","w", stdout);
//    #endif
    fast
    int n;
    cin>>n;
    int fact[n];
    int w=1;
    int mod=1000000007;
    fact[0]=0;
    forr(i,1,n) {w*=i; w%=mod; fact[i]=w;}
    int a[n];
    map<int,int> m;
    int b[n];
    forr(i,0,n) { cin>>a[i]; b[i]=a[i];}
    sort(b,b+n);
    forr(i,0,n) m[b[i]]=i+1;
    forr(i,0,n)
    {
        a[i]=m[a[i]];
    }
    ordered_set <int> s;
    int na2s=n-1;
    int ans=0;
    forr(i,0,n)
    {
        int x=a[i]-1;
        //cout<<x<<' '<<s.order_of_key(x)<<endl;
        x-=s.order_of_key(a[i]);
        x*=fact[na2s]%mod;
        x%=mod;
     //   cout<<x<<' '<<endl;
        ans+=x;
        ans%=mod;
        s.insert(a[i]);
        na2s--;
    }
    cout<<(ans+1)%mod;
    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