Submission #1119428

#	Time	Username	Problem	Language	Result	Execution time	Memory
1119428		TrieTr	Fancy Fence (CEOI20_fancyfence)	C++14	30 / 100	26 ms	4940 KiB

fancyfence

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

void local() {
    #define taskname ""
    if (fopen(taskname".inp", "r")) {
        freopen(taskname".inp", "r", stdin);
        freopen(taskname".out", "w", stdout);
    }
}

#define ll long long
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

template<class X, class Y> bool mini(X &a, const Y &b) {return (a > b) ? a = b, true : false;}
template<class X, class Y> bool maxi(X &a, const Y &b) {return (a < b) ? a = b, true : false;}

const int N = 1e6 + 5;
const int mod = 1e9 + 7;
void add(int& x, int y) {
	if((x += y) >= mod) x -= mod;
}

int n, h[N], w[N], dp[N], ri[N];
ll pf[N];

int inv2 = 5e8 + 4;
int cal(int x) {
	return 1ll * x * (x + 1) % mod * inv2 % mod;
}

int main() {
    fastio; local();
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> h[i];
    for(int i = 1 ;i <= n; i++) cin >> w[i], pf[i] = pf[i - 1] + w[i];
    stack<int> st;
	for(int i = n; i > 0; i--) {
		while(!st.empty() && h[st.top()] >= h[i]) st.pop();
		ri[i] = st.empty() ? n + 1 : st.top();
		st.emplace(i);
	}
	int res = 0;
	for(int i = n; i > 0; i--) {
		add(res, 1ll * cal(w[i]) * cal(h[i]) % mod);
		add(res, 1ll * (pf[ri[i] - 1] - pf[i]) % mod * w[i] % mod * cal(h[i]) % mod);
		add(res, dp[ri[i]] * w[i]);
		add(dp[i], dp[ri[i]]);
		add(dp[i], 1ll * (pf[ri[i] - 1] - pf[i - 1]) % mod * h[i] % mod);
	}
	cout << res;
}

Compilation message (stderr)

fancyfence.cpp: In function 'void local()':
fancyfence.cpp:7:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    7 |         freopen(taskname".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
fancyfence.cpp:8:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 |         freopen(taskname".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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