Submission #466378

#	Time	Username	Problem	Language	Result	Execution time	Memory
466378		niloyroot	Cryptography (NOI20_crypto)	C++14	14 / 100	1081 ms	7876 KiB

Crypto

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pl = pair<ll,ll>;
using vi = vector<ll>;
using ml = map<ll,ll>;
const ll mod=1000000007;
#define pb push_back
#define forp(i,a,b) for(ll i=a;i<=b;i++)
#define forn(i,a,b) for(ll i=a;i>=b;i--)
#define read(a,n) forp(i,1,n){cin>>a[i];}
#define newl '\n'
#define form(m,it) for(auto it=m.begin();it!=m.end(); it++)
#define ff first
#define ss second

void solve(){
    ll n; cin>>n;
    ll p[n+1];
    forp(i,1,n){
        cin>>p[i];
    }
    ll fact[n+1]; fact[0]=1;
    forp(i,1,n){
        fact[i]=i*fact[i-1]; fact[i]%=mod;
    }
    ll a1,ans=0,c=0;
    forp(i,1,n){
        a1=1; c=0;
        forp(j,i+1,n){
            if(p[j]<p[i]){
                c++;
            }
        }
        a1*=c; a1%=mod;
        a1*=fact[n-i]; a1%=mod;
        ans+=a1; ans%=mod;
    }
    cout<<ans+1<<newl;
}

int main() {
    clock_t start,end;
    start=clock();
    ios_base::sync_with_stdio(false); 
    cin.tie(NULL); 
    // #ifndef ONLINE_JUDGE
    //     freopen("input.txt", "r", stdin);
    //     freopen("output3.txt", "w", stdout);
    // #endif
    ll t=1;
    //cin>>t;
    while(t--){
        solve();
    }
    end=clock();
    //cout<<newl<<"Time : "<<double(end - start)/double(CLOCKS_PER_SEC)<<newl;
}

Compilation message (stderr)

Crypto.cpp: In function 'int main()':
Crypto.cpp:43:13: warning: variable 'start' set but not used [-Wunused-but-set-variable]
   43 |     clock_t start,end;
      |             ^~~~~
Crypto.cpp:43:19: warning: variable 'end' set but not used [-Wunused-but-set-variable]
   43 |     clock_t start,end;
      |                   ^~~

• Subtask 1: 5 / 5
• Subtask 2: 9 / 9
• Subtask 3: 0 / 10
• Subtask 4: 0 / 11
• Subtask 5: 0 / 21
• Subtask 6: 0 / 13
• Subtask 7: 0 / 19
• Subtask 8: 0 / 12