Submission #1168631

#	Time	Username	Problem	Language	Result	Execution time	Memory
1168631		vibeduck	Cryptography (NOI20_crypto)	C++20	21 / 100	1095 ms	7496 KiB

Crypto

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

#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define int long long
#define all(x) (x).begin(), (x).end()

typedef long double ld;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<bool>> vvb;
typedef vector<vector<ll>> vvll;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<char> vc;
typedef vector<vector<char>> vvc;
typedef map<int, int> mii;
typedef unordered_map<int, int> umii;

const int mod = 1e9 + 7;
const int inf = INTMAX_MAX;
const bool tc = false;

const int mxn = 3e5 + 5;
int fac[mxn];

void pcomp() {
    fac[0] = 0; fac[1] = 1;
    for (int i = 2; i < mxn; i++) {
        fac[i] = fac[i - 1] * i;
        fac[i] %= mod;
    }
}

inline void solve() {
    int n; cin >> n;
    vi p(n); for (int i = 0; i < n; i++) cin >> p[i];
    int ans = 1; vi s(n);

    for (int i = 0; i < n - 1; i++) {
        int sm = 0;
        for (int j = 0; j < p[i]-1; j++) sm += (1 - s[j]);
        int r = n - 1 - i;
        ans += (sm * fac[r])%mod;
        ans %= mod;
        s[p[i]-1] = 1;
    }
    cout << ans << '\n';
}

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

signed main() {
    ios::sync_with_stdio(false);
    cout.tie(0);
    cin.tie(0);
    pcomp();
    //setIO();

    int t = 1;
    if (tc) {
        cin >> t;
    }

    while (t--) {
        solve();
    }
}

Compilation message (stderr)

Crypto.cpp: In function 'void setIO(std::string)':
Crypto.cpp:61:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   61 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Crypto.cpp:62:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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