Submission #1013111

#	Time	Username	Problem	Language	Result	Execution time	Memory
1013111		Gromp15	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	18 ms	3940 KiB

fancyfence

#include <bits/stdc++.h>
#define ll long long
#define ar array
#define db double
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define rint(l, r) uniform_int_distribution<int>(l, r)(rng)
template<typename T> bool ckmin(T &a, const T &b) { return a > b ? a = b, 1 : 0; }
template<typename T> bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }
const int mod = 1e9+7, nax = 1e5 + 5;
int tp = -1;
ar<int, 2> stk[nax];
int f(int x) {
	return ((ll)x*(x+1)/2)%mod;
}
int mul(int a, int b) {
	return (ll)a*b%mod;
}
void fadd(int &a, int b) {
	a += b;
	if (a >= mod) a -= mod;
}
void fsub(int &a, int b) {
	a -= b;
	if (a < 0) a += mod;
}
void test_case() {
	int n; cin >> n;
	vector<int> h(n), w(n);
	for (int &x : h) cin >> x;
	for (int &x : w) cin >> x;
	int ans = 0, t = 0;
	for (int i = 0; i < n; i++) {
		fadd(ans, mul(f(h[i]), f(w[i])));
		int L = 0;
		while (tp >= 0 && stk[tp][0] >= h[i]) {
			fsub(t, mul(f(stk[tp][0]), stk[tp][1]));
			fadd(L, stk[tp][1]);
			tp--;
		}
		fadd(ans, mul(t, w[i]));
		fadd(ans, mul(mul(f(h[i]), L), w[i]));
		fadd(L, w[i]);
		stk[++tp] = {h[i], L};
		fadd(t, mul(f(h[i]), L));
	}
	cout << ans << '\n';


}
int main() {
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
//    cin >> t;
    while (t--) test_case();
}

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