Submission #945715

#	Time	Username	Problem	Language	Result	Execution time	Memory
945715		Sandarach151	Fancy Fence (CEOI20_fancyfence)	C++17	60 / 100	19 ms	3936 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;

#define int long long

const int MODD = 1e9+7;
const int INV = 5e8+4;

int mult(int n){
	int temp = 1;
	temp *= (n);
	temp %= MODD;
	temp *= (n+1);
	temp %= MODD;
	temp *= INV;
	temp %= MODD;
	return temp;
}

signed main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int n;
	cin >> n;
	int h[n];
	int w[n];
	bool same = true;
	bool less = true;
	for(int i=0; i<n; i++){
		cin >> h[i];
		if(i>0 && h[i]!=h[i-1]){
			same = false;
		}
		if(i>0 && h[i]<h[i-1]){
			less = false;
		}
	}
	for(int i=0; i<n; i++){
		cin >> w[i];
	}
	if(n<=1000){
		int ans = 0;
		for(int i=0; i<n; i++){
			int temp = mult(w[i]);
			temp %= MODD;
			temp *= mult(h[i]);
			temp %= MODD;
			ans += temp;
			ans %= MODD;
		}
		for(int i=0; i<n; i++){
			int minn = h[i];
			for(int j=i+1; j<n; j++){
				minn = min(minn, h[j]);
				int temp = w[i]*w[j];
				temp %= MODD;
				temp *= mult(minn);
				temp %= MODD;
				ans += temp;
				ans %= MODD;
			}
		}
		cout << ans << '\n';
	}
	else if(same){
		int summ = 0;
		for(int i=0; i<n; i++){
			summ += w[i];
			summ %= MODD;
		}
		int ans = mult(h[0]);
		ans *= mult(summ);
		ans %= MODD;
		cout << ans << '\n';
	}
	else if(less){
		int ans = 0;
		for(int i=0; i<n; i++){
			int temp = mult(w[i]);
			temp %= MODD;
			temp *= mult(h[i]);
			temp %= MODD;
			ans += temp;
			ans %= MODD;
		}
		int summ = 0;
		for(int i=0; i<n; i++){
			summ += w[i];
			summ %= MODD;
		}
		for(int i=0; i<n; i++){
			summ -= w[i];
			summ += MODD;
			summ %= MODD;
			int temp = w[i]*summ;
			temp %= MODD;
			temp *= mult(h[i]);
			temp %= MODD;
			ans += temp;
			ans %= MODD;
		}
		cout << ans << '\n';
	}	
	return 0;
}

• Subtask 1: 0 / 0
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 18 / 18
• Subtask 7: 0 / 27