Submission #126060

#	Time	Username	Problem	Language	Result	Execution time	Memory
126060		Mahmoud_Adel	Calvinball championship (CEOI15_teams)	C++14	100 / 100	279 ms	888 KiB

teams

#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
typedef long long ll;
const int N = 1e4+5, mod = 1e6+7;
ll n, dp[2][N][2], a[N];
ll sol(int i, ll j, int bit)
{
	/*
	if(i == n) return 1;
	ll &ret = dp[i][j][bit];
	if(ret != -1) return ret;
	if(bit) ret = j*sol(i+1, j, 1)%mod + sol(i+1, j+1, 1)%mod;
	else ret = (a[i]-1)*sol(i+1, max(j, a[i]-1), 1)%mod + 
	sol(i+1, max(j, a[i]), 0)%mod;
	return ret%mod;
	*/
	for(int i=0; i<=n; i++) dp[n%2][i][0] = dp[n%2][i][1] = 1LL;
	for(int i=n-1; i>=0; i--)
	{
		for(ll j=0; j<=i; j++)
		{
			dp[i%2][j][1] = j*dp[(i+1)%2][j][1] + dp[(i+1)%2][j+1][1], dp[i%2][j][1] %= mod;
			dp[i%2][j][0] = (a[i]-1)*dp[(i+1)%2][max(j, a[i]-1)][1] +
			dp[(i+1)%2][max(j, a[i])][0];
			dp[i%2][j][0] %= mod;
		}
	}
	return dp[0][0][0]%mod;
}
int main()
{
	memset(dp, -1, sizeof dp);
	cin >> n;
	for(int i=0; i<n; i++) cin >> a[i];
	cout << sol(0, 0, 0) << endl;
}

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