제출 #693729

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
693729		saayan007	Cryptography (NOI20_crypto)	C++17	48 / 100	1088 ms	11984 KiB

Crypto

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vpi = vector<pi>;
using vpl = vector<pl>;

#define fur(i, a, b) for(ll i = a; i <= (ll) b; ++i)
#define ruf(i, a, b) for(ll i = a; i >= (ll) b; --i)
#define fr first
#define sc second
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define nl "\n"

const ll mod = 1e9L + 7;
const ll mxn = 3e5L + 5;

ll n;
pl p[mxn];
ll fact[mxn];

ll mul(const ll &a, const ll &b) {
    ll c = (a % mod) * (b % mod);
    c %= mod;
    if(c < 0)
        c += mod;
    return c;
}

ll sum(const ll &a, const ll &b) {
    ll c = (a % mod) + (b % mod);
    c %= mod;
    if(c < 0)
        c += mod;
    return c;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n;
    fur(i, 1, n) {
        cin >> p[i].fr;
        p[i].sc = i;
    }
    sort(p + 1, p + n + 1);
    ll a[n + 1];
    fur(i, 1, n) {
        a[p[i].sc] = i;
    }

    fact[0] = fact[1] = 1;
    fur(i, 2, n) {
        fact[i] = mul(fact[i - 1], i);
    }

    ll dp[n + 1] = {};
    ll res =0;
    fur(i, 1, n) {
        ll smaller = a[i] - 1;
        fur(j, 1, i - 1) {
            if(a[j] < a[i]) {
                --smaller;
            }
        }
        dp[i] = mul(smaller, fact[n - i]);
        res = sum(res, dp[i]);
    }
    res = sum(res, 1);
    cout << res << nl;
}

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