Submission #975501

#	Time	Username	Problem	Language	Result	Execution time	Memory
975501		AliHasanli	Cryptography (NOI20_crypto)	C++17	100 / 100	538 ms	34136 KiB

Crypto

#include<bits/stdc++.h>
using namespace std;
map<int,int>mp;
long long fact[300005];
long long a[300005],b[300005],seg[300005*4];
long long query(long long n,long long l,long long r,long long ql,long long qr)
{
    if(l>r || ql>qr || r<ql || l>qr)return 0;
    if(ql<=l && r<=qr)return seg[n];
    return query(2*n,l,(l+r)/2,ql,qr)+query(2*n+1,(l+r)/2+1,r,ql,qr);
}
void update(long long n,long long l,long long r,long long pos)
{
    if(l>r || r<pos || l>pos)return;
    if(l==r){seg[n]=1;return;}
    update(2*n,l,(l+r)/2,pos),update(2*n+1,(l+r)/2+1,r,pos);
    seg[n]=seg[2*n]+seg[2*n+1];
}
void fac(long long n)
{
    fact[0]=1;
    for(long long i=1;i<=300004;i++)
    fact[i]=(i*fact[i-1])%1000000007;
}
int main()
{
    fac(300004);
    long long n;
    cin>>n;
    for(long long i=0;i<n;i++)
    {
        cin>>a[i];
        b[i]=a[i];
    }
    sort(b,b+n);
    for(long long i=1;i<=n;i++)
    mp[b[i-1]]=i;
    long long cavab=1;
    for(long long i=0;i<n;i++)
    {
        //cout<<fact[n-i-1]<<" "<<query(1,1,n,1,mp[a[i]])+1<<endl;
        long long sira=mp[a[i]]-query(1,1,n,1,mp[a[i]]);
        cavab+=(fact[n-i-1]*(sira-1))%1000000007;
        cavab%=1000000007;
        update(1,1,n,mp[a[i]]);
    }
    cout<<cavab;
    return 0;
}


/*
4!*(1-1)+3!(4-1)+2!(1-1)+1!(2-1)+0!(1-1)+1=18+1+1=20;

*/

• 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