Submission #442918

#	Time	Username	Problem	Language	Result	Execution time	Memory
442918		colossal_pepe	Zapina (COCI20_zapina)	C++17	110 / 110	157 ms	2272 KiB

zapina

#include <iostream>
#include <cstring>
using namespace std;

typedef long long ll;

const ll MOD = 1000000007;

ll n, C[355][355], dp[355][355];

void fillC() {
    C[0][0] = 1;
    for (int i = 1; i < 355; i++) {
        C[i][0] = C[i][i] = 1;
        for (int j = 1; j < 355; j++) {
            C[i][j] = C[i - 1][j - 1] + C[i - 1][j];
            C[i][j] %= MOD;
        }
    }
}

void setup() {
    memset(dp, -1, sizeof(dp));
    for (int i = n + 1; i < 355; i++) {
        dp[i][0] = 1;
        for (int j = 1; j < 355; j++) {
            dp[i][j] = 0;
        }
    }
}

ll modMinus(ll a, ll b) {
    ll ans = a%MOD - b%MOD;
    if (ans < 0) ans += MOD;
    return ans;
}

ll ways(ll x) {
    ll ans = 1;
    for (int i = 0; i < x; i++) {
        ans *= x;
        ans %= MOD;
    }
    return ans;
}

ll badWays(ll p, ll t) {
    if (dp[p][t] != -1) return dp[p][t];
    dp[p][t] = 0;
    for (int i = 0; i <= t; i++) {
        if (i == p) continue;
        dp[p][t] += C[t][i] * badWays(p + 1, t - i);
        dp[p][t] %= MOD;
    }
    return dp[p][t];
}

int main() {
    fillC();
    cin >> n;
    setup();
    cout << modMinus(ways(n), badWays(1, n)) << endl;
    return 0;
}

• Subtask 1: 22 / 22
• Subtask 2: 33 / 33
• Subtask 3: 55 / 55