Submission #389983

#	Time	Username	Problem	Language	Result	Execution time	Memory
389983		talant117408	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	90 ms	4640 KiB

fancyfence

/*
    Code written by Talant I.D.
*/
#include <bits/stdc++.h>
 
using namespace std;

typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
 
#define precision(n) fixed << setprecision(n)
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define mp make_pair
#define eps (double)1e-9
#define PI 2*acos(0.0)
#define endl "\n"
#define sz(v) int((v).size())
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define do_not_disturb ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define OK cout << "OK" << endl;
 
const int mod = 1e9+7;
 
ll mode(ll a) {
    a %= mod;
    if (a < 0) a += mod;
    return a;
}
 
ll subt(ll a, ll b) {
    return mode(mode(a)-mode(b));
}
 
ll add(ll a, ll b) {
    return mode(mode(a)+mode(b));
}
 
ll mult(ll a, ll b) {
    return mode(mode(a)*mode(b));
}
 
ll binpow(ll a, ll b) {
    ll res = 1;
    while (b) {
        if (b&1) res = mult(res, a);
        a = mult(a, a);
        b >>= 1;
    }
    return res;
}

const int N = 1e5+7;
ll h[N], w[N], dp[N];
int n;

int main() {
	do_not_disturb
	
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> h[i];
	}
	for (int i = 1; i <= n; i++) {
		cin >> w[i];
	}
	
	stack <pii> st;
	ll ans = 0;
	ll sum = 0;
	
	for (int i = 1; i <= n; i++) {
		ll additional = 0;
		while (!st.empty() && st.top().first > h[i]) {
			additional = add(additional, st.top().second);
			sum = subt(sum, mult(mult(st.top().first, st.top().first+1), mult(st.top().second, binpow(2, mod-2))));
			st.pop();
		}
		ans = add(ans, mult(mult(mult(h[i], h[i]+1), mult(w[i], w[i]+1)), binpow(4, mod-2)));
		ans = add(ans, mult(sum, w[i]));
		ans = add(ans, mult(mult(additional, w[i]), mult(h[i], mult(h[i]+1, binpow(2, mod-2)))));
		sum = add(sum, mult(mult(h[i], mult(h[i]+1, binpow(2, mod-2))), add(additional, w[i])));
		st.push(mp(h[i], add(additional, w[i])));
	}
	
	cout << ans;
	
    return 0;
}

• 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