Submission #1265856

#	Time	Username	Problem	Language	Result	Execution time	Memory
1265856		dio_2	Fancy Fence (CEOI20_fancyfence)	C++20	12 / 100	1 ms	328 KiB

fancyfence

#include<bits/stdc++.h>

const int MOD = int(1e9) + 7;
const int64_t INV_2 = 500000004;

int f(int a, int b){
	a = a % MOD;
	b = b % MOD;
	return int64_t(a) * (a + 1) % MOD * INV_2 % MOD * int64_t(b) * (b + 1) % MOD * INV_2 % MOD;
}

int main(){
	using namespace std;
	ios::sync_with_stdio(false), cin.tie(nullptr);
	
	int n;
	cin >> n;
	
	vector<int> h(n), w(n);
	int all_1 = 1;
	for(int i = 0;i < n;i++) cin >> h[i];
	for(int i = 0;i < n;i++) {
		cin >> w[i];
		all_1 &= (w[i] == 1);
	}
	
	int ans = 0;
	
	for(int i = 0;i < n;i++){
		int l = i, r = i;
		int64_t sL = 0;
		int64_t sR = 0;
		while(l - 1 >= 0 && h[l - 1] >= h[i]){
			l -= 1;
			sL += w[l];
		}
		while(r + 1 < n && h[r + 1] > h[i]){
			r += 1;
			sR += w[r];
		}
		// but it must strictly contain me
		sL %= MOD;
		sR %= MOD;
		if(w[i] == 1)
			ans += f(h[i], w[i]) * int64_t(sL+1) % MOD * int64_t(sR+1) % MOD;
		else {
			ans += h[i] * 1ll * (h[i] + 1) % MOD * int64_t(sL+1) % MOD * int64_t(sR+1) % MOD;
			if(ans >= MOD) ans -= MOD;
			if(w[i] > 2) ans += f(h[i], w[i] - 2);
			if(ans >= MOD) ans -= MOD;
		}
	}
	
	cout << ans << '\n';
	
	return 0;
}

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