Submission #1265880

#	Time	Username	Problem	Language	Result	Execution time	Memory
1265880		mingga	Discharging (NOI20_discharging)	C++20	0 / 100	68 ms	8264 KiB

Discharging

// Author: caption_mingle
#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define ll long long
const int mod = 1e9 + 7;
const int inf = 2e9;
const int N = 1e6 + 7;
int n, a[N], dp[N];

double ite(pair<double, double> A, pair<double, double> B) {
	// cerr << A.fi << ' ' << A.se << ' ' << B.fi << ' ' << B.se << ln;
	return (B.se - A.se) / (A.fi - B.fi);
}

bool bad(pair<double, double> A, pair<double, double> B, pair<double, double> C) {
	return ite(A, B) >= ite(A, C);
}

signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	#define task ""
	if(fopen(task ".INP", "r")) {
		freopen(task ".INP", "r", stdin);
		freopen(task ".OUT", "w", stdout);
	}
	cin >> n;
	for(int i = 1; i <= n; i++) cin >> a[i];
	deque<pair<double, double>> hull;
	hull.pb({n, 0});
	int mx = 0;
	for(int i = 1; i <= n; i++) {
		mx = max(mx, a[i]);
		while(sz(hull) >= 2) {
			if(ite(hull[0], hull[1]) <= mx) hull.pop_front();
			else break;
		}
		dp[i] = hull[0].fi * mx + hull[0].se;
		while(sz(hull) >= 2) {
			if(bad(hull[sz(hull) - 2], hull.back(), make_pair(n - i, dp[i]))) hull.pop_back();
			else break;
		}
		// cerr << n - i << ' ' << dp[i] << ln;
		hull.pb({n - i, dp[i]});
	}
	cout << dp[n] << ln;
    cerr << "\nTime: " << clock() * 1000 / CLOCKS_PER_SEC;
}

Compilation message (stderr)

Discharging.cpp: In function 'int main()':
Discharging.cpp:31:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |                 freopen(task ".INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Discharging.cpp:32:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |                 freopen(task ".OUT", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 13
• Subtask 3: 0 / 25
• Subtask 4: 0 / 11
• Subtask 5: 0 / 14
• Subtask 6: 0 / 28