Submission #964256

#	Time	Username	Problem	Language	Result	Execution time	Memory
964256		penguin133	Calvinball championship (CEOI15_teams)	C++17	100 / 100	437 ms	876 KiB

teams

#include <bits/stdc++.h>
using namespace std;
 
#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
 
int n, A[10005], dp[2][10005][2];
 
const int mod = 1e6 + 7;
/*
int c(int x, int cur, bool f){
	if(x == n + 1)return 1;
	if(dp[x][cur][f] != -1)return dp[x][cur][f];
	int ans = 0;
	if(f){
		if(cur < A[x])ans += c(x + 1, cur + 1, f & (cur + 1 == A[x]));
		if(cur){
			if(cur >= A[x])ans += (A[x] - 1) * c(x + 1, cur, 0) + c(x + 1, cur, 1);
			else ans += cur * c(x + 1, cur, 0);
		}
		ans %= mod;
	}
	else ans += c(x + 1, cur, 0) * cur + c(x + 1, cur + 1, 0), ans %= mod;
	//cout << x << ' ' << cur << ' ' << f << ' ' << ans << '\n';
	return dp[x][cur][f] = ans;
}
*/
void solve(){
	cin >> n;
	for(int i = 1; i <= n; i++)cin >> A[i];
	memset(dp, -1, sizeof(dp));
	for(int i = 0; i <= n; i++)dp[(n + 1) & 1][i][0] = dp[(n + 1) & 1][i][1] = 1;
	for(int i = n; i >= 1; i--){
		for(int j = 0; j <= n; j++){
			for(int k = 0; k < 2; k++){
				int ans = 0;
				if(k){
					if(j < A[i])ans += dp[(i + 1) & 1][j + 1][(j + 1 == A[i])];
					if(j){
						if(j >= A[i])ans += (A[i] - 1) * dp[(i + 1) & 1][j][0] + dp[(i + 1) & 1][j][1];
						else ans += j * dp[(i + 1) & 1][j][0];
					}
				}
				else ans += dp[(i + 1) & 1][j][0] * j + dp[(i + 1) & 1][j + 1][0];
				dp[i & 1][j][k] = ans % mod;
			}
		}
	}
	//cout << c(1, 0, 1);
	cout << dp[1][0][1];
}
 
main(){
	ios::sync_with_stdio(0);cin.tie(0);
	int tc = 1;
	//cin >> tc;
	for(int tc1=1;tc1<=tc;tc1++){
		// cout << "Case #" << tc1 << ": ";
		solve();
	}
}

Compilation message (stderr)

teams.cpp:60:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   60 | main(){
      | ^~~~

• 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