Submission #46446

#	Time	Username	Problem	Language	Result	Execution time	Memory
46446		alex99	Calvinball championship (CEOI15_teams)	C++14	10 / 100	6 ms	1064 KiB

teams

#include <iostream>
using namespace std;
int N;
int A[10005];
int DP[10005];
int Fact[10005], Inv[10005];
const int MOD = 1000007;
int Power[10005];
int Nb[10005];
int C[2][1005];
int power(int n, int p)
{
    int sol = 1;
    while(p)
    {
        if(p % 2 == 1)
        {
            sol = (1LL * sol * n) % MOD;
        }
        p /= 2;
        n = (1LL * n * n) % MOD;
    }
    return sol;
}
void Read()
{
    cin >> N;
    for(int i = 1; i <= N; i++)
        cin >> A[i];
}
void precalcFact()
{
    Fact[0] = 1;
    for(int i = 1; i <= N; i++)
        Fact[i] = (1LL * Fact[i - 1] * i) % MOD;
    Inv[N] = power(Fact[N], MOD - 2);
    for(int i = N - 1; i >= 0; i--)
    {
        Inv[i] = (1LL * Inv[i + 1] * (i + 1)) % MOD;
    }
}

int Comb(int n, int k)
{
    return C[n][k];
}
inline void Add(int& x, int y)
{
    x += y;
    if(x >= MOD)
        x -= MOD;
}
void precalcDP()
{
    DP[0] = 1;
    for(int i = 1; i <= N; i++)
    {
        for(int j = 0; j < i; j++)
        {
            Add(DP[i], (1LL * DP[i - 1 - j] * Comb(i - 1, j)) % MOD);
        }
    }
}
void precalcComb()
{
    for(int i = 0; i <= N; i++)
        C[i][0] = 1;
    for(int i = 1; i <= N; i++)
        for(int j = 1; j <= i; j++)
        {
            C[i][j] = C[i - 1][j - 1] + C[i - 1][j];
            if(C[i][j] >= MOD)
                C[i][j] -= MOD;
        }
}
void Solve()
{
    int nb = 1, ans = 1;
    Nb[1] = 1;
    for(int i = 2; i <= N; i++)
    {
        if(A[i] == Nb[i - 1] + 1)
            Nb[i] = Nb[i - 1] + 1;
        else
            Nb[i] = Nb[i - 1];
    }
    int ind = 0;
    C[0][0] = 1;
    for(int i = N; i >= 2; i--, ind = 1 - ind)
    {
        if(A[i] == 1)
            continue;
        int aux = 0;
        int pw = 1;
        if(i < N)
        {
            for(int j = N - i; j >= 1; j--)
            {
                C[ind][j] = C[1 - ind][j - 1];
                Add(C[ind][j], C[1 - ind][j]);
            }
            C[ind][0] = 1;
            int x = N - i;
            for(int j = 0; j < x; j++)
            {
                Add(DP[x], (1LL * DP[x - 1 - j] * C[1 - ind][j]) % MOD);
            }
        }
        for(int j = N - i; j >= 0; j--)
        {
            Add(aux, (1LL * C[ind][j] * DP[j] * pw) % MOD);
            pw = (1LL * pw * Nb[i - 1]) % MOD;
        }
        Add(ans, (1LL * aux * (A[i] - 1)) % MOD);
    }
    cout << ans << "\n";
}
int main()
{
    Read();
    precalcFact();
   // precalcComb();
    precalcDP();
    Solve();
    //cout << DP[N] << "\n";
    return 0;
}

Compilation message (stderr)

teams.cpp: In function 'void Solve()':
teams.cpp:78:9: warning: unused variable 'nb' [-Wunused-variable]
     int nb = 1, ans = 1;
         ^~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10