Submission #1043143

#	Time	Username	Problem	Language	Result	Execution time	Memory
1043143		Whisper	Cryptography (NOI20_crypto)	C++17	100 / 100	100 ms	42436 KiB

Crypto

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define REPD(i, a) for (int i = (a) - 1; i >= 0; --i)

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)


constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

/*
    Phu Trong from Nguyen Tat Thanh High School for gifted student
*/

template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }

template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }
#define MAX             300005
int nArr;

int A[MAX];

vector<int> comp;

int find(int x){
    return lower_bound(comp.begin(), comp.end(), x) - comp.begin() + 1;
}


int fac[MAX];

struct FenwickTree{
    vector<int> F;
    int n;
    FenwickTree(int _n = 0){
        init(n);
    }
    void init(int _n = 0){
        F.clear();
        this -> n = _n;
        F.resize(n + 5);
    }
    int low_bit(int p){
        return p & (-p);
    }
    void upd(int p){
        for (; p <= n; p += low_bit(p)) F[p] ++;
    }
    int query(int p){
        int res = 0;
        for (; p > 0; p -= low_bit(p)) res += F[p];
        return res;
    }
};

int mul(int x, int y){
    return 1LL * x * y % Mod;
}
void add(int &x, int y){
    x += y;
    if (x >= Mod) x %= Mod;
}

void process(void){
    cin >> nArr;
    for (int i = 1; i <= nArr; ++i) {
        cin >> A[i];
        comp.push_back(A[i]);
    }
    sort(comp.begin(), comp.end());
    comp.resize(unique(comp.begin(), comp.end()) - comp.begin());

    fac[0] = 1;
    for (int i = 1; i <= nArr; ++i) fac[i] = fac[i - 1] * i % Mod;

    int ans = 0;
    FenwickTree ft(nArr);
    for (int i = 1; i <= nArr; ++i){
        A[i] = find(A[i]);
        int val = mul(A[i] - 1 - ft.query(A[i]), fac[nArr - i]);
        add(ans, val);
        ft.upd(A[i]);
    }
    add(ans, 1);
    cout << ans;
}
signed main(){
    #define name "Whisper"
    cin.tie(nullptr) -> sync_with_stdio(false);
    //freopen(name".inp", "r", stdin);
    //freopen(name".out", "w", stdout);
    process();
    return (0 ^ 0);
}

Compilation message (stderr)

Crypto.cpp: In function 'void process()':
Crypto.cpp:56:13: warning: 'ft.FenwickTree::n' may be used uninitialized in this function [-Wmaybe-uninitialized]
   56 |         init(n);
      |         ~~~~^~~
Crypto.cpp:56:13: warning: 'ft.FenwickTree::n' may be used uninitialized in this function [-Wmaybe-uninitialized]

• 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