Submission #43992

#	Time	Username	Problem	Language	Result	Execution time	Memory
43992		sorry_Benq	Calvinball championship (CEOI15_teams)	C++17	100 / 100	132 ms	1104 KiB

teams

#include <bits/stdc++.h>
#define int long long
using namespace std;
typedef long long ll;
const int MOD = 1e6 + 7;

ll a[10005];
ll DP[10005];
ll mxs[10005];

/*int solve(int N, int K){
	//you have N numbers left, and they can start anywhere from 1 - K.
	if (DP[N][K] != 0) return DP[N][K];
	if (N == 0) return 1;
	else{
		return DP[N][K] = (((long long) K)*solve(N - 1, K) + solve(N - 1, K + 1))%MOD;
	}
}*/

int cnt = 10005; 
void evolve(){
	for (int i = 0; i < cnt - 1; i++){
		DP[i] = ((long long) i)*DP[i] + DP[i + 1];
		DP[i] %= MOD;
	}
	cnt--;
}



main(){
	int N; cin >> N;
	for (int i = 0; i < N; i++){
		cin >> a[i];
	}
	for (int i = 0; i < cnt; i++){
		DP[i] = 1;
	}
	ll res = 1;
	int mx = 1;
	for (int i = 0; i < N; i++){
		mxs[i] = mx;
		mx = max(mx, a[i]);
	}
	for (int i = N - 1; i >= 0; i--){
		//matches prefix of length i
		res += ((ll) a[i] - 1)*DP[mxs[i]];
		evolve();
		res %= MOD;
	}
	cout << res << endl;
}

Compilation message (stderr)

teams.cpp:31:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 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