Submission #1026368

#	Time	Username	Problem	Language	Result	Execution time	Memory
1026368		Whisper	Binaria (CCO23_day1problem1)	C++17	25 / 25	243 ms	115284 KiB

Main

#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, n) for (int i = 0; i < (a); ++i)
#define REPD(i, n) 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 = 1e6 + 3;
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         1000005

int N, K, M;
int A[MAX];


int inv[MAX], fac[MAX];
int power(int a, int exp){
    int res = 1;
    for (;exp > 0; a = (a * a) % Mod, exp >>= 1) if(exp & 1){
        res = (res * a) % Mod;
    }
    return res;
}
void genFac(int n){
    fac[0] = 1;
    for (int i = 1; i <= n; ++i) fac[i] = fac[i - 1] * i % Mod;
    inv[n] = power(fac[n], Mod - 2);
    for (int i = n - 1; i >= 0; --i) inv[i] = inv[i + 1] * (i + 1) % Mod;
}

int C(int n, int k){
    if (n < k || k < 0) return 0;
    return fac[n] * inv[k] % Mod * inv[n - k] % Mod;
}
void mul(int &x, int y){
    x = (1ll * x * y) % Mod;
}
void add(int &x, int y){
    x += y;
    if (x >= Mod) x -= Mod;
}

vector<int> G[MAX];

int col[MAX];
int vis[MAX];
void paint(int u, int c){
    vis[u] = 1; col[u] = c;
    for (int&v : G[u]) if(!vis[v]){
        paint(v, c);
    }
}
void process(void){
    cin >> N >> K;
    M = N - K + 1;
    for (int i = 1; i <= M; ++i) cin >> A[i];
    genFac(N);
    for (int i = 1; i <= N; ++i) col[i] = -1;
    for (int i = 1; i < M; ++i){
        if(A[i] == A[i + 1]){
            G[i].push_back(i + K);
            G[i + K].push_back(i);
        }
        else if(A[i] + 1 == A[i + 1]){
            col[i] = 0, col[i + K] = 1;
        }
        else if(A[i] - 1 == A[i + 1]){
            col[i] = 1, col[i + K] = 0;
        }
        else return void(cout << 0);
    }
    vector<int> vis(K + 5);
    for (int i = 1; i <= N; ++i){
        if (~col[i]){
            paint(i, col[i]);
        }
    }
    for (int i = 1; i < M; ++i){
        if (A[i] == A[i + 1]){
            if(col[i] != col[i + K]) return void(cout << 0);
        }
        else if (A[i] < A[i + 1]) {
            if(!(col[i] == 0 && col[i + K] == 1)) return void(cout << 0);
        }
        else{
            if(!(col[i] == 1 && col[i + K] == 0)) return void(cout << 0);
        }
    }

    int need = A[1], emp = 0;
    for (int i = 1; i <= K; ++i){
        if (col[i] == -1) emp++;
        else if(col[i] == 1) need--;
    }

    assert(emp >= 0);
    cout << C(emp, need);
}
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);
}

• Subtask 1: 3 / 3
• Subtask 2: 3 / 3
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 7 / 7